The P0323 OBD-II trouble code means the Powertrain Control Module has detected an intermittent signal from the ignition or distributor engine-speed input circuit.
The generic definition for P0323 is:
Ignition/Distributor Engine Speed Input Circuit Intermittent
Unlike P0322, which indicates that the expected engine-speed signal is completely missing, P0323 means the signal appears, disappears or becomes unstable while the PCM is monitoring it.
Depending on the vehicle, the engine-speed input may originate from the:
- Crankshaft position sensor
- Camshaft position sensor
- Distributor pickup
- Ignition control module
- Dedicated engine-speed sensor
- Wiring connecting these components to the PCM
Common symptoms include random stalling, hard starting, tachometer dropout and an engine that shuts off when hot but restarts after cooling down.
A failed position sensor is possible, but intermittent wiring, loose terminals and temperature-sensitive ignition modules are equally capable of triggering P0323. Randomly replacing whichever sensor is easiest to reach remains an option, of course—just not a particularly intelligent one.
P0323 Quick Facts
| Item | Information |
|---|---|
| Trouble code | P0323 |
| Generic definition | Ignition/Distributor Engine Speed Input Circuit Intermittent |
| System | Ignition and engine-speed monitoring |
| Fault type | Intermittent signal dropout |
| Severity | Moderate to severe |
| Safe to drive? | Not recommended if the engine stalls |
| Common symptoms | Random stalling, hard starting, tachometer dropout |
| Common causes | Loose connector, damaged wiring, failing sensor or ignition module |
| Primary diagnostic tool | Scan tool and oscilloscope |
| Related codes | P0320, P0321, P0322 and P0335 |
What Does the P0323 Code Mean?
The PCM relies on engine-speed and position signals to determine:
- Engine RPM
- Crankshaft position
- Ignition timing
- Fuel-injector timing
- Misfire detection
- Variable valve timing
- Automatic transmission operation
- Tachometer output on some vehicles
A properly functioning sensor produces a consistent series of electrical pulses while the crankshaft or distributor rotates.
With P0323, that signal is not continuously absent. Instead, it drops out, becomes erratic or disappears briefly before returning.
The interruption may last only a fraction of a second. That is still enough to confuse the PCM, interrupt ignition operation or shut down the engine.
How the Engine-Speed Signal Works
Modern engines typically use a crankshaft position sensor mounted near a toothed reluctor wheel. As the wheel rotates, the sensor generates a repeating electrical pattern.
The PCM uses that pattern to calculate engine speed and crankshaft position.
Depending on the application, the sensor may be:
Hall-Effect Sensor
A Hall-effect sensor normally uses:
- A voltage supply
- A ground circuit
- A digital signal circuit
Its output switches between high and low voltage as the reluctor teeth pass the sensor.
Magnetic Pickup Sensor
A magnetic sensor generally uses two wires and produces an alternating-current waveform. Signal voltage increases as engine speed rises.
Distributor Pickup
Distributor-equipped engines may use a magnetic or Hall-effect pickup inside the distributor. The signal may travel through an ignition control module before reaching the PCM.
If any part of that signal path becomes unstable, the PCM may store P0323.
What Does “Intermittent” Mean?
An intermittent fault occurs only under certain conditions or for short periods.
The signal may fail when:
- The engine reaches operating temperature
- The vehicle travels over rough pavement
- The wiring harness moves
- Engine vibration increases
- Moisture enters a connector
- Electrical load changes
- The sensor or ignition module becomes hot
- A damaged terminal loses contact
- Engine movement pulls on the harness
The vehicle may operate normally during inspection. That makes P0323 more difficult to diagnose than a permanent open or short circuit.
The code is essentially reporting that the engine-speed signal briefly left work without telling anyone.
P0323 Versus P0321, P0322 and P0335
These codes describe related but different signal failures.
| Code | Definition | Diagnostic distinction |
| P0320 | Ignition/distributor engine-speed input circuit malfunction | General circuit fault |
| P0321 | Engine-speed input circuit range/performance | Signal exists but behaves implausibly |
| P0322 | Engine-speed input circuit no signal | Expected signal is continuously missing |
| P0323 | Engine-speed input circuit intermittent | Signal repeatedly drops out and returns |
| P0335 | Crankshaft position sensor “A” circuit malfunction | Fault assigned specifically to CKP sensor A |
Keeping these distinctions clear prevents the pages from competing for the same search intent.
P0323 should focus on finding a signal that fails because of heat, vibration, terminal tension or another intermittent condition. General crankshaft-sensor circuit diagnosis belongs with the P0335 crankshaft position sensor “A” guide.
How Serious Is the P0323 Code?
P0323 can become a serious safety concern because an intermittent engine-speed signal may cause the engine to stall without warning.
Possible consequences include:
- Sudden engine shutdown
- Loss of ignition spark
- Loss of injector pulse
- Failure to restart
- Reduced power-steering assistance
- Reduced brake assistance
- Poor transmission operation
- Unpredictable starting problems
If the engine stalls while driving, do not continue operating the vehicle until the fault has been diagnosed.
A vehicle that runs normally after restarting is not necessarily repaired. Intermittent faults are extremely skilled at pretending nothing happened once the hood is open.
Common Symptoms of P0323
P0323 symptoms may include:
- Check Engine Light
- Random engine stalling
- Engine stalls after warming up
- Engine restarts after cooling down
- Hard starting
- Extended cranking
- Intermittent crank-no-start condition
- Tachometer drops suddenly
- Scan-tool RPM briefly falls to zero
- Engine hesitation
- Sudden loss of power
- Rough running
- Ignition misfire
- Transmission shifting problems
- No spark during the failure
- No injector pulse during the failure
- Other crankshaft, camshaft or ignition codes
For a complete symptom-based diagnosis, see our guides covering an engine that stalls while driving and an engine that cranks but will not start.
Common Causes of the P0323 Code
The most common P0323 causes include:
- Failing crankshaft position sensor
- Heat-sensitive crankshaft sensor
- Failing camshaft position sensor
- Defective distributor pickup
- Failing ignition control module
- Loose sensor connector
- Weak connector-terminal tension
- Corroded terminals
- Backed-out connector pin
- Broken wire inside the insulation
- Wiring damaged by engine vibration
- Wiring melted near the exhaust
- Harness rubbing against a bracket
- Intermittent sensor power supply
- Intermittent sensor ground
- Excessive ground-circuit resistance
- Oil or coolant inside a connector
- Water intrusion
- Excessive sensor-to-reluctor air gap
- Damaged reluctor wheel
- Loose or moving reluctor
- Distributor shaft wear
- Loose sensor mounting
- Poor PCM connection
- PCM software problem
- Internal PCM failure
Intermittent connector and wiring problems deserve special attention. A circuit can pass a stationary continuity test and still fail when the engine moves, heats up or vibrates.
Common Vehicles Affected by P0323
P0323 is a generic OBD-II powertrain code and can appear on vehicles from many manufacturers, including:
- Audi
- Volkswagen
- Mercedes-Benz
- Ford
- Chevrolet
- GMC
- Chrysler
- Dodge
- Jeep
- Hyundai
- Kia
- Nissan
- Infiniti
- Toyota
- Lexus
The component associated with the code varies by application. Some vehicles monitor a direct crankshaft-sensor signal, while others receive a processed engine-speed signal through the ignition module or distributor.
Always identify the correct circuit using manufacturer wiring diagrams and service information.
Common P0323 Scan-Tool Patterns
Intermittent faults are easier to diagnose when live data is graphed rather than viewed as a changing number.
RPM Suddenly Drops to Zero
One of the strongest P0323 patterns is an engine RPM parameter that suddenly falls to zero while the crankshaft is still rotating.
Possible causes include:
- Sensor signal dropout
- Loss of sensor power
- Loss of sensor ground
- Open signal circuit
- Loose connector
- Ignition-module failure
Graph the RPM signal while reproducing the stalling or hesitation event.
RPM Becomes Erratic Before Stalling
The scan tool may show RPM jumping rapidly before the engine stops.
Possible causes include:
- Weak magnetic-sensor output
- Excessive sensor air gap
- Damaged reluctor teeth
- Electrical interference
- Loose sensor
- Distributor shaft movement
- Wiring intermittently shorting
RPM Returns After Cooling
The engine may stall hot, display no cranking RPM and then restart after sitting for several minutes.
This pattern frequently suggests a component that fails internally as its temperature rises, including:
- Crankshaft position sensor
- Distributor pickup
- Ignition control module
- Damaged terminal connection
Heat-related behavior is useful evidence, but it does not identify the failed part by itself.
RPM Changes During a Wiggle Test
If RPM data becomes unstable while the harness or connector is gently moved, inspect that area for:
- Broken conductor strands
- Loose terminals
- Corrosion
- Poor connector retention
- Previous wiring repairs
- Harness tension
Do not aggressively pull the wiring while the engine is running. The objective is to reveal the existing fault, not create a fresh one for next week.
RPM Remains Normal
If engine RPM remains stable during the fault, investigate whether the vehicle uses another ignition-reference parameter.
The affected signal may originate from:
- Ignition control module output
- Distributor reference circuit
- Camshaft position input
- Manufacturer-specific engine-speed channel
Generic scan data does not display every monitored input.
How to Diagnose the P0323 Code
Diagnosing P0323 requires capturing the failure while it occurs or finding physical evidence of an intermittent connection.
Step 1: Scan Every Available Module
Connect a capable scan tool and record:
- Stored codes
- Pending codes
- History codes
- Freeze-frame data
- Engine RPM
- Cranking RPM
- Battery voltage
- Camshaft and crankshaft synchronization
- Ignition-reference parameters
- Misfire counters
- Module communication faults
Do not clear the code before saving this information.
Freeze-frame data may reveal whether P0323 occurred during:
- Initial startup
- Idle
- Acceleration
- Highway driving
- Deceleration
- High engine temperature
- Low system voltage
Related codes may help identify whether the failure affects one sensor, a shared power circuit or the entire ignition system.
Step 2: Verify Battery and Charging-System Health
Check:
- Battery state of charge
- Cranking voltage
- Charging voltage
- Battery-terminal condition
- Engine ground
- Body ground
- PCM grounds
- Ignition-module grounds
Low voltage or a poor ground can interrupt sensor and module operation.
Many vehicles require cranking voltage to remain above approximately 9.6 volts, but always use the manufacturer’s specification.
Voltage-drop testing is more useful than checking resistance alone because it tests the circuit while current is flowing.
Step 3: Identify the Engine-Speed Signal Source
Use the correct wiring diagram to identify:
- Which component generates the signal
- Whether an ignition module processes it
- Which PCM terminal receives it
- Whether power or ground circuits are shared
- Whether the tachometer uses the same signal
- Whether related sensors share a reference voltage
Do not assume P0323 always identifies the crankshaft position sensor.
Depending on the vehicle, the problem may involve the distributor pickup, ignition module or another engine-speed input circuit.
Step 4: Monitor Engine RPM
Graph engine RPM during:
- Cold startup
- Warmup
- Idle
- Acceleration
- Deceleration
- Hot restart
- Road testing
Watch for:
- Sudden zero-RPM readings
- Unexplained RPM spikes
- Signal dropout before stalling
- Cranking with no RPM displayed
- RPM returning after the vehicle cools
If the engine stalls, note whether RPM disappears before or after the engine actually stops rotating.
If the signal drops before the engine stops, it may be the cause of the stall. If RPM reaches zero only after the engine stops, it may simply be reporting the result.
Step 5: Inspect the Wiring and Connectors
Inspect the complete signal path between the sensor, ignition module and PCM.
Look for:
- Damaged insulation
- Melted wiring
- Harness contact with the exhaust
- Harness contact with pulleys or belts
- Tight bends
- Stretched wiring
- Loose connector locks
- Bent terminals
- Backed-out pins
- Green corrosion
- Oil contamination
- Coolant intrusion
- Water damage
- Poor aftermarket splices
- Previous collision repairs
Pay special attention to wiring near:
- Exhaust manifolds
- Engine mounts
- Transmission bellhousings
- Distributor bodies
- Timing covers
- Starter motors
- Battery cables
Engine movement can pull on a harness that appears normal while the vehicle is parked.
Step 6: Perform a Wiggle Test
With the engine running or cranking, monitor:
- Engine RPM
- Sensor signal
- Ignition-reference status
- Cam/crank synchronization
Gently move individual harness sections and connectors.
If the engine stumbles or the signal changes, isolate the affected section.
A successful wiggle test is useful, but avoid disturbing several connectors simultaneously. Move one area at a time so the result can be traced to an actual location.
Step 7: Check Terminal Tension
A connector may look clean and fully seated while one terminal makes poor contact.
Inspect for:
- Spread female terminals
- Partially backed-out pins
- Broken terminal locks
- Connector-body damage
- Fretting corrosion
- Weak contact pressure
Use the manufacturer-approved terminal test tool when available. Forcing an oversized probe into the terminal can spread it and manufacture the very fault you are trying to diagnose.
Step 8: Test Power and Ground
If the vehicle uses a Hall-effect sensor or powered ignition module, verify its supply voltage and ground during the failure.
Monitor the circuits while:
- Cranking
- Idling
- Warming the engine
- Moving the harness
- Applying electrical loads
A momentary loss of power or ground may be too brief for a basic multimeter to capture. A graphing meter or oscilloscope is more effective.
If several sensors share the same reference circuit, disconnect them individually to determine whether another component is intermittently pulling the circuit down.
Step 9: Inspect the Signal With an Oscilloscope
An oscilloscope is the most effective tool for diagnosing P0323 because it displays signal interruptions that a multimeter may average out.
A healthy waveform should show:
- Consistent amplitude
- Even pulse spacing
- Clean transitions
- A repeating pattern
- No unexpected gaps
- No excessive electrical noise
Look for:
- Missing pulses
- Signal dropping flat
- Voltage spikes
- Weak amplitude
- Signal stuck high
- Signal stuck low
- Waveform changes as the sensor heats up
- Waveform changes when the harness moves
Compare the waveform at the sensor and PCM.
If the waveform is correct at the sensor but fails at the PCM, the wiring or an intermediate ignition module is likely responsible.
If the signal fails directly at the sensor, inspect sensor power, ground, mounting and the reluctor before replacing it.
Step 10: Perform a Heat Test
If the fault occurs only after the engine warms up, carefully test temperature-sensitive components.
Monitor the waveform while the component reaches normal operating temperature.
A technician may use controlled heat or cooling spray to reproduce the failure, but excessive heat can damage sensors, wiring and plastic connectors. Follow established electrical-testing procedures.
A signal that disappears predictably as a sensor or ignition module heats up provides strong evidence of an internal component failure.
Step 11: Inspect the Reluctor and Sensor Air Gap
A sensor cannot produce a stable waveform if its mechanical trigger is damaged.
Inspect for:
- Missing reluctor teeth
- Cracked reluctor
- Loose reluctor
- Excessive runout
- Metallic debris
- Incorrect sensor installation
- Loose mounting hardware
- Excessive sensor air gap
- Crankshaft endplay
- Distributor shaft wear
A moving reluctor or worn distributor shaft may produce a fault only at certain engine speeds.
Step 12: Test the Ignition Control Module
If the signal passes through an ignition control module, verify:
- Module power
- Module ground
- Sensor input
- Module output
- Connector integrity
- Operation at different temperatures
If the module receives a stable sensor signal but intermittently stops sending the engine-speed output, the module or its output circuit may be faulty.
Step 13: Verify the PCM Input
PCM replacement should only be considered after verifying:
- Battery voltage
- Ground integrity
- Sensor operation
- Sensor waveform
- Reluctor condition
- Wiring continuity
- Terminal tension
- Ignition-module output
If a clean signal reaches the correct PCM terminal while scan data shows a dropout, investigate:
- PCM connector problems
- Software updates
- Technical service bulletins
- Internal PCM failure
Controller failure is possible, but it should be proven—not selected because everything else became inconvenient.
Why P0323 Can Be Difficult to Diagnose
A permanent electrical failure is usually easier to locate because the circuit remains failed during testing.
P0323 may disappear when:
- The vehicle is parked
- The engine cools
- The harness stops moving
- The connector dries
- Electrical load decreases
- The hood is opened
Standard resistance testing may show a normal circuit even when a conductor is broken internally. The wire can reconnect when relaxed and separate again as the engine moves.
Successful diagnosis often requires:
- Graphing scan data
- Capturing waveforms
- Road testing
- Heat-soak testing
- Wiggle testing
- Checking terminal tension
- Monitoring voltage over time
Common Diagnostic Mistakes
Avoid these common mistakes:
- Replacing the crankshaft sensor without confirming signal loss
- Clearing freeze-frame data before recording it
- Inspecting connectors without checking terminal tension
- Testing the vehicle only while cold
- Using only a stationary continuity test
- Ignoring battery and ground problems
- Confusing P0323 with P0322
- Assuming a stalled engine automatically proves sensor failure
- Failing to compare the signal at the sensor and PCM
- Replacing the PCM before testing its inputs
- Overlooking damaged reluctor teeth
- Ignoring an ignition control module in the signal path
An intermittent fault requires evidence gathered during the failure. Otherwise, diagnosis becomes an expensive series of educated guesses with increasingly less education.
How to Fix the P0323 Code
The correct repair depends on where the engine-speed signal becomes unstable.
Possible repairs include:
- Repairing a broken signal wire
- Replacing damaged harness sections
- Cleaning corroded connectors
- Replacing loose electrical terminals
- Repairing sensor power or ground
- Securing a loose connector
- Rerouting wiring away from the exhaust
- Replacing a failing crankshaft position sensor
- Replacing a defective camshaft position sensor
- Replacing a distributor pickup
- Replacing an ignition control module
- Repairing or replacing a reluctor wheel
- Correcting sensor alignment or air gap
- Repairing PCM connectors
- Updating PCM software
- Replacing and programming the PCM when proven defective
After repairing the fault:
- Clear all stored codes.
- Start the engine and monitor RPM.
- Allow the engine to reach operating temperature.
- Repeat the conditions shown in the freeze-frame data.
- Perform a road test.
- Shut the engine off and complete a hot restart.
- Rescan for pending and stored codes.
Because P0323 is intermittent, one successful startup is not enough to verify the repair.
Estimated P0323 Repair Costs
Repair costs depend on the vehicle and failed component.
| Repair | Typical estimated cost |
| Electrical diagnosis | $100–250 |
| Connector or terminal repair | $75–300 |
| Wiring-harness repair | $100–600 |
| Crankshaft position sensor | $150–450 |
| Camshaft position sensor | $150–400 |
| Distributor pickup repair | $200–600 |
| Ignition control module | $200–700 |
| Reluctor wheel repair | $500–2,000+ |
| PCM replacement and programming | $800–2,500+ |
These estimates include broad parts-and-labor ranges. Sensor location and diagnostic time can significantly affect the final price.
Can You Drive With a P0323 Code?
Driving with P0323 is not recommended when the vehicle stalls, loses power or becomes difficult to restart.
A brief engine-speed signal interruption may disable spark and injector operation. If that happens while driving, the engine can shut down without warning.
Move the vehicle to a safe location and arrange diagnosis if it exhibits:
- Repeated stalling
- Tachometer dropout
- Hot no-start condition
- Sudden loss of power
- No spark
- No injector pulse
If the Check Engine Light is the only symptom, limit driving until the code can be investigated.
Can P0323 Cause Random Stalling?
Yes. Random stalling is one of the most important symptoms associated with P0323.
When the PCM loses the engine-speed signal, it may stop controlling:
- Ignition spark
- Injector pulse
- Fuel-pump operation
- Ignition timing
The engine may restart immediately, restart after cooling or remain in a crank-no-start condition.
For broader symptom-based testing, use the Pro Street Car Symptoms Encyclopedia.
Can a Bad Crankshaft Sensor Cause P0323?
Yes. A crankshaft position sensor that fails intermittently can trigger P0323.
Heat can cause an internal sensor winding or electronic circuit to open temporarily. Once the sensor cools, the connection may return and allow the engine to restart.
However, the same behavior can be caused by:
- Loose connector terminals
- Broken wiring
- Poor sensor ground
- Ignition-module failure
- Reluctor damage
- PCM connection problems
Confirm the signal dropout before replacing the sensor.
Can a Weak Battery Cause P0323?
Low system voltage can interfere with the sensor, ignition module or PCM, especially during cranking.
Check battery condition when P0323 occurs with:
- Slow cranking
- Low-voltage codes
- Multiple unrelated trouble codes
- Module communication faults
- Electronic resets
A weak battery is less likely to cause a single intermittent failure while driving, but battery terminals, charging-system connections and grounds should still be inspected.
Does P0323 Always Mean the Sensor Is Bad?
No.
P0323 reports intermittent signal loss. It does not identify which component interrupted the signal.
The actual fault may be:
- Sensor failure
- Wiring damage
- Loose terminal
- Poor ground
- Ignition-module failure
- Reluctor problem
- PCM input fault
Replacing the sensor without testing the circuit may leave the original problem untouched.
Will P0323 Cause a Misfire?
P0323 can cause hesitation, rough running or misfire-like symptoms if the engine-speed signal becomes unstable.
However, cylinder-specific misfires are more commonly caused by ignition coils, spark plugs, injectors, air leaks or compression problems.
For a complete misfire diagnosis, see Engine Misfire Symptoms, Causes and Diagnosis.
Related Pro Street Diagnostic Guides
Continue the diagnosis with these related resources:
- Complete P-series OBD-II code list
- P0315 crankshaft position system variation not learned
- P0322 engine-speed input circuit no signal
- P0335 crankshaft position sensor “A” circuit malfunction
- Engine cranks but will not start
- Engine misfire symptoms, causes and diagnosis
- Bad ignition coil symptoms
- How to test a Ford Focus crank sensor
- How to test a Chrysler Concorde crank sensor
Final Thoughts
The P0323 code means the PCM has detected an intermittent ignition or distributor engine-speed input signal.
Unlike P0322, where the signal is missing continuously, P0323 describes a signal that drops out and returns. That makes heat-sensitive sensors, loose terminals, damaged wiring and failing ignition modules especially important.
Begin by recording freeze-frame data and graphing engine RPM. Inspect terminal tension, perform a controlled wiggle test and monitor the waveform as the engine reaches operating temperature.
Do not replace the crankshaft sensor merely because its name appears somewhere in the diagnostic family tree. Find the exact point where the signal disappears and repair that fault. Electricity may be invisible, but the invoice from guessing certainly will not be.
