Idle control in your vehicle is controlled by your ECU or PCM. Controlling several different components, there can be a number of issues that can lead to a P0505 trouble code. When you have idle problems and your check engine light turns on, you will need an OBDII scan tool to pull the code. Should this code come back as a P0505, you’ve got to fix your throttle signal before your vehicle returns to normal.
The problem is, sometimes it can be difficult to fix P0505 problems because there are so many parts that go into idle. Whether you own an older vehicle with mechanical idle control systems or a late model vehicle, the challenge still remains. Despite the challenge, the goal is the same. Restore your vehicle idle or erase your P0505 check engine light.
What causes P0505 trouble codes?
Depending on the generation of your vehicle, there are many components that help control idle. If you’ve got passages built into your intake manifold, your ECU no doubt employs a valve to dictate engine speed. Sometimes this can be adjusted by way of an idle speed screw or idle adjustment.
In more modern vehicles, idle speed is controlled by an Idle Air Control Motor or stepper motor. That doesn’t mean that the P0505 error code is caused only by the failure of the idle air controller. Want to erase your check engine light and fix your P0505 trouble code? Let’s take a look at how you can begin your troubleshooting process.
P0505 Symptoms
- Engine will not idle properly
- Hard to start engine
- Idle fluctuates or is very low
- Engine idle speed is rough or uneven
- High idle – uncontrollable idle
Before you begin troubleshooting the P0505 engine code, you need to figure out if you’ve got a modern idle control, or an early one. Should your vehicle employ an earlier model idle speed control system, you should check the function of your idle motor first. If your idle stepper motor checks out okay, clean the intake manifold passages that this valve uses.
Should your idle control valve fail, you will need to replace it. Need a guide on how to fix P0505 trouble codes by testing your idle air controller? Make sure to check my guides through the OBDII DTC Doctor on my website for more information.
To raise or lower the engine Idle speed, your PCM (Powertrain Control Module) modulates the idle air controller or stepper motor.
Common Causes of P0505 Code
- Defective Idle Air Control Motor
- Bad idle air controller wiring
- Intake Manifold Vacuum leaks
- Dirty intake manifold passages
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