P0506 is a common OBDII trouble code. It is typically triggered when the engine idle speed is lower than the predetermined limit set by the manufacturer.
It is a generic code, which means that it has the same meaning for the Mitsubishi Lancer as it would any other vehicle.
P0506 Symptoms: Lancer
Most of the time, P0506 be noticeable to you when driving. Here are the typical symptoms for the Lancer:
- Service Engine Soon Light– The reason why you are here.
- Lower Idle Speed– Assuming that the code has been thrown due to a legitimate issue, you should notice the engine running slower when not pushing the gas.
- Stalling– The idle may be too slow for the car to run without pressing on the accelerator pedal.
Mitsubishi Lancer P0506 Causes and Diagnosis
There are a lot of potential causes to P0506. While the code specifically mentions the “Idle Air Control System”, it would be a mistake to just go ahead and replace the idle air control valve without a little due diligence. It’s not always the cause of the code.
Here are some of the most common causes of P0506 in the Mitsubishi Lancer, as well as waist to troubleshoot them. Keep in mind that there are differences in model years. It would be a good idea to start by looking for a vacuum leak and move forward from there.
Vacuum Leak
A leaking vacuum system will often cause the Lancer to idle higher. When the vacuum system leaks, it throws off the air balance in the combustion chamber.
How to Find a Vaccum Leak in a Vehicle (Popular Mechanics, Article)
How to Find a Vacuum Leak in about a Minute (2CarPros, YouTube)
A vacuum leak can come from bad vacuum hose, the intake manifold, EGR System, or about anywhere else that air flows through. It’s not hard to find a vacuum leak though. Use the resources above and you’ll find it in no time.
Idle Air Control Valve
Most modern fuel injected engines are equipped with an idle air control valve. Not all of them are though. If you have determined that you don’t have a vacuum leak, the IAC is a great second place to troubleshoot P0506. Idle air control valves are relatively affordable.
How to Diagnose an IAC Valve (Autozone Guides)
Throttle Body
A throttle body opens and closes millions of times in the life of a vehicle. All of the air that passes through it can slowly cause it to collect grime. This grime can change the idle characteristics of the vehicle. When dirty, you’ll often feel the vehicle almost stall before the computer compensates and opens it a little more.
Alternatively, if the throttle body has been damaged, it may not be properly regulating air flow, and the code may be thrown.
Signs Your Throttle Body Is Going Bad, and What to Do (Repair Pal)
How to Tell if Your Throttle Body is Dirty or Bad (YouTube Auto Repair, Youtube)
Intake and/or Exhaust Blocked
There could be an issue with the catalytic converter, or a clogged intake manifold that can cause the idle to drop and throw P0506.
Conclusion
P0506 is a serious issue. Due to the unsafe nature of driving with an engine that can stall at any time, we recommend having your Lancer serviced as soon as possible. Good luck!