Cars rarely fail without warning. They shake, smoke, smell, hesitate, grind, overheat, leak, vibrate, or illuminate the dashboard like a slot machine before something expensive happens.
The Pro Street Car Symptoms Encyclopedia helps you identify possible problems based on what your vehicle is doing—not just the diagnostic trouble code stored in its computer.
Select the symptom that best matches your vehicle to see:
- The most common causes
- Warning signs to watch for
- Step-by-step diagnostic checks
- Related OBD-II trouble codes
- Repair urgency
- Whether the vehicle is safe to drive
- Frequently asked questions
A symptom cannot always identify one failed component, but it can tell you which system to investigate first. That’s considerably more useful than replacing random parts until the problem disappears—or your checking account does.
Important: This guide provides general diagnostic information. Stop driving if the vehicle has low oil pressure, severe overheating, brake failure, heavy smoke, a flashing Check Engine light, a strong fuel smell, or another immediate safety warning.
Start With What Your Car Is Doing
Choose the category that most closely matches your vehicle’s symptoms.
Engine Performance Symptoms
Engine performance problems can affect starting, idling, acceleration, fuel economy, and drivability. Many are caused by ignition, fuel, airflow, emissions, sensor, or internal engine failures.
Car Shakes While Idling
A car that shakes while idling may have an engine misfire, vacuum leak, dirty throttle body, clogged fuel injector, or worn engine mount.
If engine speed fluctuates, investigate how the engine is running. If RPM remains steady but the cabin vibrates, inspect the engine and transmission mounts.
Read: Why Does My Car Shake While Idling?
Car Won’t Accelerate
Poor acceleration may be caused by restricted airflow, low fuel pressure, ignition problems, a clogged catalytic converter, transmission failure, electronic throttle faults, or reduced-power mode.
The diagnosis depends on whether the engine revs normally, struggles under load, or increases RPM without increasing vehicle speed.
Read: Why Won’t My Car Accelerate?
Engine Stalls When Warm
An engine that starts cold but stalls after warming up may have a failing crankshaft position sensor, ignition component, fuel pump, relay, idle-control system, or temperature-related electrical fault.
Heat can increase electrical resistance or cause failing internal components to stop working temporarily.
Read: Why Does My Engine Stall When Warm?
Engine Cranks but Won’t Start
If the starter turns the engine but it doesn’t start, the engine may be missing fuel, spark, compression, injector control, or correct timing.
Listen to how the engine cranks. An unusually fast or uneven cranking sound can indicate low compression or a mechanical timing problem.
Read: Engine Cranks but Won’t Start: Common Causes
Car Surges While Driving
A car that accelerates and decelerates without consistent pedal input may have a throttle-control problem, vacuum leak, unstable fuel pressure, ignition issue, transmission fault, or contaminated airflow sensor.
Surging can also occur when an automatic transmission repeatedly locks and unlocks its torque converter.
Read: Why Does My Car Surge While Driving?
Rough Idle After Refueling
Rough idling or hard starting immediately after filling the fuel tank commonly points toward a stuck EVAP purge valve.
The valve may allow excessive fuel vapor into the intake manifold, temporarily creating an overly rich air-fuel mixture.
Read: Why Does My Car Idle Rough After Refueling?
Car Dies After Fueling
A vehicle that stalls after getting gas may have a failed EVAP purge valve, saturated charcoal canister, contaminated fuel, or tank-venting problem.
Repeatedly topping off the tank after the pump stops can force liquid fuel into an EVAP system designed to handle vapor. More fuel isn’t a bonus round.
Read: Why Does My Car Die After Getting Gas?
Engine Hesitates During Acceleration
Hesitation occurs when the engine briefly loses power or responds slowly when the accelerator is pressed.
Possible causes include worn spark plugs, weak ignition coils, low fuel pressure, dirty injectors, a contaminated mass airflow sensor, throttle-position faults, or transmission problems.
Read: Why Does My Engine Hesitate When Accelerating?
Engine Misfires
An engine misfire occurs when one or more cylinders fail to produce normal combustion.
Misfires may cause shaking, hesitation, reduced power, poor fuel economy, an uneven exhaust sound, and diagnostic codes ranging from P0300 to cylinder-specific codes such as P0301.
Read: Engine Misfire Symptoms, Causes, and Diagnosis
Engine Loses Power While Driving
Sudden or gradual power loss may be related to fuel starvation, a restricted catalytic converter, turbocharger failure, overheating, electronic throttle problems, incorrect timing, or transmission trouble.
A vehicle entering reduced-power or limp mode may intentionally limit acceleration to prevent additional damage.
Read: Why Is My Car Losing Power While Driving?
Starting and Electrical Symptoms
Starting problems can involve the battery, starter, charging system, ignition switch, immobilizer, wiring, fuel system, engine sensors, or mechanical condition.
The sounds the vehicle makes during the starting attempt provide important clues.
Car Makes One Click but Won’t Start
A single loud click usually means the starter solenoid is engaging but the starter motor isn’t turning.
Possible causes include a weak battery, corroded battery terminals, damaged cables, faulty starter, poor engine ground, or mechanically seized engine.
Read: Car Clicks Once but Won’t Start
Car Makes Rapid Clicking Noise
Rapid clicking usually indicates that battery voltage is dropping too low to keep the starter solenoid engaged.
Start by testing the battery and inspecting the cable connections. A jump-start may get the engine running, but it doesn’t explain why the battery became discharged.
Read: Rapid Clicking When Starting a Car
Car Has Power but Won’t Start
Dashboard lights do not prove the battery can supply enough current to operate the starter. Headlights and electronics require far less current than cranking the engine.
A no-start condition with working accessories may still be caused by the battery, starter circuit, immobilizer, transmission range switch, or ignition switch.
Read: Car Has Power but Won’t Start
Car Starts and Immediately Dies
An engine that starts and then stalls may have an immobilizer problem, failed mass airflow sensor, vacuum leak, fuel-pressure issue, blocked throttle body, or faulty idle-control system.
Observe whether a security warning remains illuminated after the engine stops.
Read: Why Does My Car Start and Then Die?
Battery Keeps Dying
A repeatedly discharged battery may be old, undercharged, or drained by an electrical circuit that remains active while the vehicle is parked.
Common causes include charging-system failure, lights left on, aftermarket accessories, defective modules, and excessive parasitic draw.
Read: Why Does My Car Battery Keep Dying?
Exhaust Smoke Symptoms
Exhaust smoke color can reveal whether the engine is burning coolant, oil, or excessive fuel. Temperature, duration, and smell are just as important as color.
Condensation on a cold morning is normal. A persistent cloud following the car like it elected a new pope is not.
White Smoke From the Exhaust
Thin white vapor during a cold start is usually condensation. Thick white smoke that continues after the engine warms up may indicate coolant entering the combustion chambers.
Possible causes include a failed head gasket, cracked cylinder head, damaged engine block, or intake gasket failure on certain engines.
Read: White Smoke From Exhaust: Causes and Warning Signs
Blue Smoke From the Exhaust
Blue or blue-gray smoke usually means engine oil is being burned.
Common causes include worn piston rings, failed valve-stem seals, turbocharger seal failure, an overfilled crankcase, or a malfunctioning PCV system.
Smoke during startup, acceleration, or deceleration can help identify where the oil is entering the engine.
Read: Blue Smoke From Exhaust: Is the Engine Burning Oil?
Black Smoke From the Exhaust
Black exhaust smoke usually indicates excessive fuel or insufficient air.
Potential causes include leaking fuel injectors, excessive fuel pressure, a contaminated airflow sensor, restricted air filter, faulty oxygen sensor, or engine-control problem.
Diesel engines can produce black smoke under heavy load, but persistent or excessive smoke still requires diagnosis.
Read: Black Smoke From Exhaust: Common Causes
Gray Smoke From the Exhaust
Gray smoke can be caused by oil consumption, an overly rich fuel mixture, turbocharger failure, or transmission fluid entering the intake on certain older vehicles.
Because gray smoke is more difficult to classify, check fluid levels and consider whether it smells like fuel, oil, or coolant.
Read: What Causes Gray Exhaust Smoke?
Unusual Car Noises
Noises should be diagnosed by their location, pitch, frequency, and operating condition.
Determine whether the sound changes with:
- Engine speed
- Vehicle speed
- Steering input
- Brake application
- Road surface
- Transmission gear
- Acceleration or deceleration
Clicking Noise While Turning
Repeated clicking while turning commonly indicates a worn outer CV joint, especially on a front-wheel-drive or all-wheel-drive vehicle.
The noise often becomes more noticeable during tight turns under acceleration.
A single clunk may instead come from a ball joint, tie-rod end, strut mount, control-arm bushing, or loose component.
Read: Clicking Noise While Turning: Common Causes
Grinding Noise When Braking
Grinding while braking may mean the brake pads are completely worn and the backing plates are contacting the rotors.
It can also be caused by debris, damaged brake hardware, a seized caliper, or rust after the vehicle has been parked.
Because braking performance may be compromised, inspect the vehicle immediately.
Read: Grinding Noise When Braking
Whining Noise Under Acceleration
A whining sound that increases during acceleration may originate from the transmission, differential, power-steering system, alternator, turbocharger, supercharger, or accessory drive.
Check whether the pitch follows engine RPM or vehicle speed. That distinction can separate an engine-driven component from a wheel-speed-related problem.
Read: Whining Noise When Accelerating
Knocking Sound From the Engine
Engine knocking can describe several different problems, ranging from combustion detonation to bearing damage.
A deep knock that increases with engine load can indicate serious internal wear. A light metallic ping during acceleration may be caused by low-octane fuel, excessive ignition timing, overheating, or carbon deposits.
Read: Engine Knocking Noise: What It Means
Squealing When Starting or Accelerating
A high-pitched squeal often comes from a slipping serpentine belt, worn tensioner, damaged pulley, or accessory beginning to seize.
A squeal that only occurs during braking is more likely related to the brake pads or brake hardware.
Read: Why Does My Car Squeal When I Accelerate?
Humming or Growling While Driving
A humming noise that changes with vehicle speed may indicate a worn wheel bearing, uneven tire wear, differential problem, or transmission issue.
Wheel-bearing noise may change when the vehicle turns and transfers weight from one side to the other.
Read: Humming Noise While Driving
Steering, Suspension, and Vibration Symptoms
Vehicle vibration is generally connected to engine speed, road speed, braking, or steering. Identifying when the vibration occurs can eliminate entire groups of possible causes.
Steering Wheel Vibration
Steering wheel vibration may be caused by tire imbalance, bent wheels, tire damage, worn suspension parts, wheel-bearing failure, brake rotor variation, or alignment problems.
The speed or condition that triggers the vibration matters:
- At highway speed: Tires, wheels, or suspension
- While braking: Brake rotors, calipers, or suspension
- While idling: Engine performance or engine mounts
- During acceleration: Axles, mounts, tires, or driveline
Read: Why Is My Steering Wheel Shaking?
Car Shakes at Highway Speed
Vibration between roughly 50 and 75 mph commonly points toward tire imbalance, tire separation, bent wheels, or worn suspension components.
Do not assume every highway-speed vibration needs a wheel balance. A damaged tire can remain dangerous even after someone attaches additional weights to the wheel and declares victory.
Read: Why Does My Car Shake at Highway Speed?
Car Pulls to One Side
Pulling may result from unequal tire pressure, tire construction differences, incorrect alignment, brake drag, worn suspension parts, or road crown.
A sudden pull while braking requires immediate inspection because one side of the braking system may not be operating correctly.
Read: Why Does My Car Pull to One Side?
Clunking Over Bumps
Clunking over uneven roads can originate from sway-bar links, control-arm bushings, strut mounts, ball joints, shock absorbers, loose brake hardware, or exhaust components.
Inspect the suspension before assuming every clunk requires new struts.
Read: Clunking Noise When Driving Over Bumps
Car Bounces After Hitting a Bump
Excessive bouncing usually indicates weak shocks or struts. It can reduce tire contact with the road, increase braking distance, and make the vehicle harder to control.
Uneven tire wear and fluid leaking from a shock or strut support the diagnosis.
Read: Why Does My Car Keep Bouncing?
Brake Symptoms
Brake symptoms should always be treated seriously. Pulling, grinding, a soft pedal, fluid loss, or a brake warning light can indicate reduced braking capability.
Grinding When Braking
Grinding can mean the friction material is worn away and metal components are contacting the brake rotor.
Continuing to drive may damage the rotors, calipers, and other components while increasing stopping distance.
Read: Grinding Noise When Braking
Steering Wheel Shakes When Braking
A steering wheel that shakes during braking is commonly associated with uneven front brake rotor thickness or lateral runout.
Worn suspension components, sticking calipers, loose wheel bearings, and improper wheel installation can produce similar symptoms.
Read: Steering Wheel Shakes When Braking
Brake Pedal Feels Soft or Spongy
A soft brake pedal may be caused by air in the hydraulic system, a fluid leak, failing master cylinder, damaged brake hose, or overheated brake fluid.
Do not continue driving if the pedal sinks toward the floor or braking performance has noticeably decreased.
Read: Soft Brake Pedal: Causes and Safety Warnings
Brake Pedal Pulsates
Pedal pulsation commonly results from brake rotor thickness variation, improper wheel-lug torque, hub corrosion, or an anti-lock braking system event.
ABS pulsation during emergency braking can be normal. Repeated pulsation during ordinary stops is not.
Read: Why Does My Brake Pedal Pulsate?
Car Pulls When Braking
Pulling during braking can be caused by a sticking caliper, contaminated brake pad, collapsed brake hose, uneven friction material, tire problem, or worn suspension component.
This symptom can affect vehicle control and should be inspected promptly.
Read: Why Does My Car Pull When Braking?
Transmission and Drivetrain Symptoms
Transmission symptoms can resemble engine problems. The key question is whether the engine is failing to produce power or the drivetrain is failing to transfer it.
Transmission Slips
A slipping transmission allows engine RPM to rise without a matching increase in vehicle speed.
Possible causes include low transmission fluid, internal clutch wear, valve-body problems, solenoid faults, torque-converter failure, or software-related pressure control issues.
Check the fluid according to the manufacturer’s procedure. Some modern transmissions do not have a conventional dipstick because apparently checking fluid became too convenient.
Read: Transmission Slipping: Symptoms and Causes
Transmission Hesitates Before Moving
A delay when shifting into Drive or Reverse may be related to low fluid, leaking internal seals, valve-body problems, worn clutches, torque-converter drain-back, or electronic control faults.
A delay that becomes worse when cold or after the car sits overnight can provide an important clue.
Read: Transmission Delays Going Into Gear
Transmission Jerks When Shifting
Harsh or jerking shifts can result from low fluid, degraded fluid, solenoid failure, valve-body problems, worn mounts, incorrect adaptation values, or internal transmission wear.
Engine misfires and throttle-control problems can also make shifts feel unusually harsh.
Read: Why Does My Transmission Jerk When Shifting?
Clunk When Shifting Into Drive or Reverse
A clunk during gear engagement may come from worn engine mounts, transmission mounts, universal joints, CV joints, differential bushings, or excessive driveline play.
The transmission itself is only one possible source.
Read: Clunk When Shifting Into Drive or Reverse
Car Vibrates During Acceleration
Acceleration-related vibration may be caused by worn inner CV joints, damaged driveshaft components, bad engine mounts, tire problems, driveline angle issues, or an engine misfire under load.
Read: Why Does My Car Vibrate During Acceleration?
Engine Temperature and Cooling Symptoms
Cooling-system problems can destroy an engine quickly. If the temperature gauge enters the red zone or a temperature warning appears, turn off the air conditioning, safely pull over, and shut down the engine.
Never remove a pressurized radiator cap while the system is hot.
Engine Overheats at Idle
An engine that overheats while stopped but cools down while moving often has insufficient airflow through the radiator.
Common causes include:
- Failed radiator fan
- Faulty fan relay or control module
- Damaged fan wiring
- Blocked radiator
- Low coolant
- Weak water pump
- Thermostat problem
Road speed can force air through the radiator and hide a failed cooling fan.
Read: Why Does My Engine Overheat at Idle?
Engine Overheats While Driving
Overheating at speed may indicate low coolant, restricted coolant flow, a stuck thermostat, weak water pump, clogged radiator, combustion gas entering the cooling system, or excessive engine load.
Read: Why Does My Car Overheat While Driving?
Temperature Gauge Moves Up and Down
A fluctuating temperature gauge may indicate low coolant, trapped air, an intermittent thermostat, failing coolant-temperature sensor, electrical problem, or inconsistent coolant circulation.
Read: Why Is My Temperature Gauge Fluctuating?
Heater Blows Cold Air While Engine Is Hot
Cold heater output combined with an overheating engine can indicate low coolant, trapped air, a clogged heater core, thermostat problem, or failed water pump.
This combination deserves immediate attention because coolant may not be circulating correctly.
Read: Car Overheats but Heater Blows Cold Air
Car Smell Symptoms
Unusual smells can identify leaking fluids, electrical problems, overheated components, or exhaust-system failures. Never ignore a strong fuel or burning-electrical smell.
Burning Oil Smell
A burning oil smell often means engine oil is leaking onto a hot exhaust component.
Common leak sources include valve-cover gaskets, camshaft seals, crankshaft seals, oil-filter housings, turbocharger lines, and spilled oil from recent service.
Read: Burning Oil Smell From a Car
Rotten Egg Smell
A rotten egg or sulfur smell may come from an overheating catalytic converter, an overly rich fuel mixture, contaminated fuel, battery failure, or certain transmission-fluid problems.
If the odor comes from the battery area, shut the vehicle off and avoid sparks or flames. An overcharged battery can release hydrogen sulfide and other hazardous gases.
Read: Why Does My Car Smell Like Rotten Eggs?
Burning Rubber Smell
A burning rubber smell can be caused by a slipping belt, seized pulley, tire rubbing against bodywork, overheated clutch, plastic contacting the exhaust, or a hose touching a hot component.
Read: Burning Rubber Smell From a Car
Gasoline Smell
A gasoline odor may indicate a fuel leak, leaking injector, loose fuel cap, EVAP-system fault, flooded engine, or an excessively rich air-fuel mixture.
Do not drive if you see leaking fuel or the smell is strong inside or around the vehicle.
Read: Why Does My Car Smell Like Gas?
Sweet Smell From the Engine
A sweet chemical smell commonly indicates leaking engine coolant.
Inspect the radiator, hoses, expansion tank, heater core, water pump, and engine for evidence of coolant loss—but only after the system has cooled.
Read: Sweet Smell From a Car
Burning Plastic or Electrical Smell
A burning plastic smell can indicate overheated wiring, an electrical short, a failing blower motor, damaged connector, or an accessory drawing excessive current.
Shut the vehicle off if smoke appears or the smell becomes strong.
Read: Burning Electrical Smell From a Car
Fluid Leak Symptoms
Fluid color can help identify the system, but dirt, age, and pavement color can alter its appearance.
Before touching an unknown fluid, verify that it is not fuel, hot coolant, or another hazardous substance.
| Fluid appearance | Possible source |
|---|---|
| Black or brown and oily | Engine oil |
| Red or reddish-brown | Transmission or power-steering fluid |
| Green, orange, pink, blue, or yellow | Engine coolant |
| Clear water | Air-conditioning condensation |
| Clear to amber and slippery | Brake fluid |
| Strong-smelling clear or amber fluid | Gasoline or diesel fuel |
| Thick fluid near a wheel | CV-joint grease |
| Clear or blue fluid | Windshield washer fluid |
Air-conditioning condensation is normally clear, odorless water. That puddle under the passenger side may be the rare automotive fluid leak that isn’t trying to invoice you.
Oil Leak Under the Car
Oil leaks can come from gaskets, seals, oil pans, filter housings, drain plugs, turbocharger lines, or the oil filter.
Check the oil level regularly and address any leak that reaches hot exhaust components.
Read: Why Is My Car Leaking Oil?
Coolant Leak
A coolant leak may cause overheating, a sweet smell, visible steam, low heater output, or colored residue around cooling-system components.
Never continue driving an overheating engine to “see if it gets better.” It will not appreciate the experiment.
Read: How to Find a Coolant Leak
Red Fluid Under the Car
Red fluid commonly comes from an automatic transmission or hydraulic power-steering system. However, aged fluid may appear brown.
Identify the location of the leak and check the appropriate reservoir using the manufacturer’s procedure.
Read: What Is the Red Fluid Leaking From My Car?
Clear Water Under the Car
Clear water beneath the passenger side after using the air conditioner is usually normal condensation.
Water in the cabin may instead indicate a blocked evaporator drain, windshield leak, sunroof-drain problem, or heater-core failure.
Read: Why Is Water Leaking From My Car?
Dashboard Warning Symptoms
Warning lights identify the system that detected a problem, not necessarily the failed part.
Scan the vehicle and diagnose the stored data before replacing components.
Check Engine Light Is On
A steady Check Engine light means the engine or emissions computer detected a fault. The vehicle may continue to operate normally, but diagnostic codes should be retrieved as soon as practical.
Read: What Does the Check Engine Light Mean?
Check Engine Light Is Flashing
A flashing Check Engine light commonly indicates an active misfire capable of damaging the catalytic converter.
Reduce engine load, safely stop, and diagnose the vehicle before continuing.
Read: Flashing Check Engine Light: Can You Keep Driving?
Oil Warning Light Is On
The oil-pressure warning light can indicate dangerously low oil pressure. It is not simply a reminder to schedule an oil change.
Shut the engine off as soon as it is safe to do so and check the oil level. Continuing to run the engine can cause catastrophic damage.
Read: Oil Pressure Warning Light Is On
Battery Light Is On
The battery warning light generally indicates a charging-system problem, not automatically a defective battery.
Possible causes include alternator failure, belt problems, damaged wiring, poor connections, or a charging-control fault.
Read: Why Is My Battery Light On?
Temperature Warning Light Is On
A temperature warning means the engine may be overheating. Safely pull over and shut off the engine before serious damage occurs.
Read: Engine Temperature Warning Light Explained
ABS Light Is On
An illuminated ABS warning means the anti-lock braking system has detected a fault. Conventional braking may remain available, but anti-lock operation and related stability-control features may be disabled.
Read: ABS Warning Light: Causes and Diagnosis
Can a Symptom Identify the Exact Failed Part?
Usually not by itself.
One symptom can have several causes, and one failed component can produce multiple symptoms. For example, a vacuum leak may cause rough idle, stalling, hesitation, poor fuel economy, and lean diagnostic codes.
Accurate diagnosis combines several types of evidence:
- Operating condition: When does the problem occur?
- Diagnostic codes: Which system detected a fault?
- Live data: What are the sensors and control modules reporting?
- Visual inspection: Is anything loose, leaking, cracked, or damaged?
- Component testing: Does the suspected part meet specification?
- Mechanical testing: Does the engine have proper compression and timing?
Diagnostic trouble codes are clues—not legally binding confessions from the part named in the description.
How to Describe a Car Problem Accurately
Before diagnosing the vehicle, record exactly when the symptom occurs.
Ask these questions:
- Does it happen during a cold start or after warming up?
- Does it happen in Park, Neutral, Drive, or Reverse?
- Does it change with engine RPM?
- Does it change with vehicle speed?
- Does it occur during acceleration, cruising, braking, or turning?
- Does weather or outside temperature affect it?
- Did it begin after refueling, maintenance, or a repair?
- Are any warning lights illuminated?
- Are there unusual smells, noises, smoke, or leaks?
- Is the symptom constant or intermittent?
“Car runs bad” may be emotionally accurate, but it won’t narrow the diagnosis much.
“Engine shakes at 650 RPM in Drive after warming up, but smooths out above 1,000 RPM” gives you something useful to test.
When Should You Stop Driving?
Safely pull over and shut the vehicle off if you notice:
- Low oil-pressure warning
- Severe overheating
- Flashing Check Engine light
- Heavy white or blue exhaust smoke
- Strong gasoline odor
- Visible fuel leak
- Burning electrical smell or smoke
- Brake pedal sinking toward the floor
- Sudden steering difficulty
- Loud internal engine knocking
- Rapid coolant loss
- Severe loss of power
- Wheel wobble or tire separation
- Transmission unable to engage reliably
Continuing to drive may turn a manageable repair into engine, transmission, catalytic-converter, or collision damage.
Car Symptoms and OBD-II Codes Work Together
Symptom diagnosis and OBD-II diagnostics are most effective when used together.
The symptom explains what the driver experiences. The diagnostic code identifies the system where the vehicle detected an abnormal condition.
For example:
| Vehicle symptom | Related systems or codes |
|---|---|
| Car shakes while idling | P0300–P0308, P0171, P0174 |
| Car stalls when warm | P0335, P0340, fuel-pressure codes |
| Rough idle after refueling | P0440, P0441, P0446 |
| Car won’t accelerate | Throttle, airflow, fuel, boost, or transmission codes |
| Black exhaust smoke | Rich-mixture, injector, oxygen-sensor, or airflow codes |
| Engine overheats | Cooling-fan, temperature-sensor, or thermostat-related faults |
| Transmission slips | P0700 and transmission-specific codes |
Use the Pro Street OBD-II Code Encyclopedia to research stored codes, then compare the code’s possible causes with the vehicle’s actual symptoms.
Diagnose the Car Before Replacing Parts
The best diagnosis follows evidence.
Begin with basic inspections, retrieve all diagnostic codes, examine live data, and test the suspected system. Do not clear the codes until you have recorded them and their freeze-frame information.
Replacing the component mentioned in a code description is not diagnosis. It is shopping with extra steps.
The Car Symptoms Encyclopedia is designed to help you understand what the car is doing, determine how urgent the problem may be, and select the next logical test. Start with the symptom you recognize, follow the diagnostic path, and confirm the failure before ordering parts.
