Hey Forum,

I bought a 2007 Infiniti G35X Sedan just over a month ago now. My Dad and I serviced the car by cleaning both Mass Airflow Sensors and Throttle Bodies using special sprays, and also poured some Fuel Injector Cleaner into the gas tank.

About 2 weeks later I got the "Service Engine Soon" light. A friend of mine whos a mechanic checked it out and returned the error code P0507 - "Idle Air Control System RPM Higher Than Expected".

I went online and found multiple ways to reset this (Idle Relearn). I managed to reset the light and lower my RPM's at Idle to about 700RPMs but after driving for a few minutes the light came back on and I idled at 1000RPM. A day later my mechanic plugged in his computer to the car and with it performed an Idle Relearn and although the results appeared to be successful the RPM's shot back up to 1000 at idle only an hour later.

I went to get a complimentary 100-point inspection at my local Infiniti Dealer too gain some insight and here's what they said: my CAT Converter has a crack and my O2 sensors need to be replaced. They didn't even mention anything about the error code. I only noted my car's symptoms.

My dad and I lifted the car up later and saw no cracks on the CAT and doubts the O2 sensors are bad. He thinks that it will just take time for the RPM's to go down on their own after our cleaning.

Do you think the CAT or O2 sensors have anything to do with this? Should I keep trying the Idle Relearn procedure? What about unplugging the battery for a day?

Much appreciated!

 

Did you REMOVE the throttle body or just wipe it down while it was installed? If it was really gunked up and you actually sprayed TB cleaner into the throttle body as opposed to spraying it on a rag and wiping it down then you may have forced debris into the tiny passageway for the idle air control valve and clogged it.

Couple other possibilities, did you use actual MAF cleaner to clean the MAF and TB cleaner to clean the TB? Using carb cleaner to clean either of them will likely destroy or damage the MAF and spraying carb cleaner into the engine while it's running is notorious for damaging O2 sensors.

Which fuel injector cleaner did you use and was it added to a FULL tank of fuel?

You can ask if the dealership "smoke tested" the exhaust, if that's how they found the crack then it's pretty much guaranteed to be cracked, it might have a cracked GASKET though and the information was wrongly explained to you.

Also, the rpm's will probably not just "go down on their own", your engine is reporting a malfunction in the system which means something is worn/broken or not hooked up properly.

 

We removed both black hoses connecting to the TB and then sprayed TB cleaner inside the TB. Then we used a rag to wipe out any debris, which was very little. Is it possible to get to the idle air control valve to see if its clogged? How big of a job is that?

We used CRC MAF cleaner for the MAF and TB cleaner for the TB. We sprayed the MAF cleaner on the MAF and then popped them back into the hoses a few seconds after.

I can't recall the brand but I think we added it to a full tank. I didn't think much of it when we poured it in.

I'll ask them today. If it is cracked, how does this increase the rpm's?

Thanks for the response, much appreciated.

 

Your postcat or precat O2 sensors need to be replaced?

Usually, if the relearn doesn't take it means a bad throttle body from what I have read. But, since the dealer said your O2 sensors and CAT has a crack it could messing with your idle.

If you have a live data scanner, I would see if your car goes into closed loop mode and what the fuel trims are at. Better yet, I would ask the dealer to provide you with the data they used to determine that.

I believe the idle air control valve is integrated in the throttle body. Did you touch the butterfly valve at all? Usually, I turn the car on, press the pedal, and then clean the TB that way without touching it. I did it once the other way it took forever to get the relearn to takel