Opel Signum P0507: Idle Air Control – RPM Higher than Expected

P0507 Opel Signum

P0507 is a fairly typical OBDII trouble code. It is typically triggered when the engine idle speed is 200 rpm or more over the predetermined limit set by the manufacturer. It is a generic code, which means that it has the same for the Opel Signum as any other vehicle.


P0507 Symptoms

Unlike many OBDII trouble codes, P0507 will typically be noticeable to you when driving. Here are the typical symptoms for the Signum:

  • Service Engine Soon Light– The reason why you are here.
  • Faster Idle Speed– Assuming that the code has been thrown due to a legitimate issue, you should notice the engine running faster when not pushing the gas.
  • Thud Going Into Drive– Transmissions really don’t like to shift from park to drive at an RPM higher than idle. It is common to feel the whole vehicle jerk when put into gear with P0507.
  • Vehicle Takes off Faster– With the engine idling higher, people report feeling the vehicle take off when releasing the brake pedal. This can make driving more dangerous.


Opel Signum P0507 Causes and Diagnosis

There are a lot of potential causes to P0507. While the code specifically mentions the “Idle Air Control System”, it would be a mistake to just go ahead and replace it without a little due diligence. The Idle Air Control Valve is often not the cause of the code.

Here are some of the most common causes of P0507 in the Opel Signum, 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 Signum to idle higher. When the vacuum system leaks, it allows extra air to enter into the combustion chamber. This air allows for a slightly higher combustion, increases the RPM and throws the code.

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 P0507.

A Typical Idle Air Control Valve

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.

A Typical Throttle Body

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)



P0507 is a serious issue. Due to the unsafe nature of driving with an engine that is revving higher than it’s supposed to, we recommend having your Signum serviced as soon as possible. Good luck!