: Code P0101

11-29-05, 07:35 PM
Recently, i had a "Check Engine (http://www.cadillacforums.com/forums/showthread.php?t=42056&highlight=p0101#)" light on. I had it scanned and it came out to be P0101 which i was told is the MAF sensor. I have a friend mechanic who works for GM (http://www.cadillacforums.com/forums/showthread.php?t=42056&highlight=p0101#) and he has the Tech2 scanner. He checked the MAF of the car if it's functioning and according to the data and I actually saw it, the MAF is sensing as it should. But even though it's sensing after clearing the codes, I still have the usual symptoms of stalling when at a stop, and intermittent loss of power. Aside from the P0101 code, i also had P0175 and P0172 which was interpreted as rich mixture in bank 1 and 2. In short, the oxygen sensors are sensing a rich mixture. Now, my friends interpretation is that even though the MAF is actually functioning, and since the ECU is reacting to whatever is reported by the MAF, he said that probably, there is initially a lean mixture of gas and air, and of course the ECU will try to balance this and so there will be more fuel injected. Now, he said that the Fuel Filter (http://www.cadillacforums.com/forums/showthread.php?t=42056&highlight=p0101#) could be clogged that is why initially, even though there are attempts to inject more fuel there isn't and then the ECU will continue to command the system to inject more and there will be instances where it will inject too much thus the "rich mixture" report by the oxygen sensors. Since we saw that the MAF is functioning, it should be okay even though the code is about the MAF. Is it possible for this to happen? Normally, when the MAF goes bad the code is P0100, mine was P0101. Is there any significance to the difference in the code? Could the observation of my friend be possible. At any rate, I will replace the fuel filter and see if it improves or solve the problem. I added a fuel system (http://www.cadillacforums.com/forums/showthread.php?t=42056&highlight=p0101#) cleaner just recently because i thought that it might help a little bit (actually used the one made by Chevron). But the symptoms still persist. Any input will be much appreciated.

11-29-05, 11:26 PM
I doubt your fuel filter is causing the problem. If it was clogging, you would experience more problems at higher speeds when fuel demand is greater.

11-30-05, 07:26 AM
The P0101 is setting because the engine is stalling.
Rich codes don't set because your system is running lean.
The computer uses the "fuel trim" to control whether it's running rich or lean.
If you look at your fuel trim values on the data list using the Tech 2 they probably read negative % that should seem high. If the codes set it could be as large as -20%. That means there is too much fuel and the ECM is trying to take fuel away. I'd start by checking the FPR. It's by far the most common failure for this type of condition.

It's probably leaking. You could also have other problems like a leaking injector or problems with the induction system. Does this have a factory air filter?

12-01-05, 11:49 PM
yes, factory air filter. its been pretty messy around here lately with slushy dirty snowy rainy roads could that mess up the air filter?
also, i just replaced my FPR with one from NAPA like a month or so ago...

ps. whats a Tech 2?

12-02-05, 07:22 AM
The Tech 2 is the factory scan tool that we use in the shop.

A visual inspection of the air filter should let you know if anything from outside is getting into it.
It would have to be pretty nasty to really affect your car that way.

You'd really need a scan tool that can show you the fuel trims to proceed on this one. From there you can try to isolate a fuel leak.
If you have the time and energy you can lift the fuel rail out of the intake, leaving the lines connected and then turn the key to "run" (don't crank it!)
A leaking injector should show up doing this but watch out for the fuel spray. Make sure there are no ignition sources present (like cigarettes or disconnected spark plug wires!)
It might be worth having a fire extinguisher on hand.... just in case.