I'm wondering if the quality of fuel , premium vs. regular, has something to do with the intermittent fault codes P0170 and P0173. Opinions in this matter are welcome. Thanks.

Darrel

These codes are usually associated with the Mass Air Flow (MAF) sensor. Have you been using only premium gas?

You most likely will have to remove the MAF, clean it with CRC MAF cleaner and reset the codes. If you have the problem again, the MAF might have to be replaced.

Frankly I've been using 87 Octane gas which is regular. I hardly use this car only 24,000 miles since 2001 (S430). I haven't work on this car yet since it was under warranty until last April. I started getting this EPC malfunction several months ago but was intermittent and it ereases itself. I am going to start with the vacuum leak test and cleaning the MAF. Is there one MAF or two.

Thanks Michael for your time and sharing your knowledge.

Darrel

Darrel,
I am not familiar with your exact model, but I expect there is only one MAF.

My opinion is that you are risking damage to the engine.

Not because regular fuel is of lesser quality, but because it burns faster and you risk detonation at higher RPMs and under load.

Your engine is tuned to run on higher octane, slower burning fuel. Putting regular in it is bad for that reason alone.



-tp

I will start using premium gas. Where can I get this CRC MAF cleaner? Is it the same as carburator cleaner? or maybe as a elcetric contact cleaner? I read there is some film with resistor inside the MAF, don't know if solvents can ruin this film and sensor.

Thank you for sharing your experience. And yes there is only one MAF. Thank you again.

Darrel