2008 Mazda 5 intermittent P2187 engine code

[ZoomZoomZ]

I am looking for help to resolve an intermittent P2187 diagnostic code issue (system too lean at idle bank 1) for a 2008 Mazda 5 (2.3L Touring) with ~120k miles.

The idle is not rough or unstable, there is no difficulty starting the engine, there is no fuel smell, no whistling or hissing noises from the engine bay and no apparent fuel economy issues.

I have replaced the following components and the code is still present.

• Engine air filter
• MAF
• EGR gasket
• Throttle body gasket
• Intake manifold runner control
• Upstream B1S1 O2 (air fuel ratio) sensor
• Purge solenoid.

A smoke test has been completed and no leaks have been found.

There are no apparent issues with the fuel filter, the fuel pump or the gas cap.

There are no other engine codes showing.

If the P2187 code is cancelled using an OBD2 scanner, the engine light will stay off for 20-100 miles (in town or highway driving), then come on with a P2187 code.

Does the group have any advice on how to diagnose and/or resolve this issue please?

 

[negusm]

You are running lean so you've most likely got a vacuum leak. Do the brake cleaner vacuum leak finder trick. This will find leaks you can't find by looking.

When was the last the hoses were changed? If not, by now, you probably have some that are rock hard.

Also, did you use a Mazda MAF or one from a big box store? Only OEM MAFs seem to work anymore. If you have your old one just be super careful and clean it.

Did you clean your Throttle Body?