Contour Enthusiasts Group Archives Forums General Troubleshooting Advice, MAF or O2 Sensor?

The other day the CEL came on, had the code read, #2 bank reading lean. Now, is it the O2 monitors, O2 Sensors or the MAF. I reset the caode and drove for several days without a problem, we even monitored the operation of the sensors with a EKG-like machine. They fluctuated between 0.02 volts to .89 volts at times. Both had periodic flat lines.

Now the delema.. what do I replace? I reset the codes and drove for several days and it came back on. When the CEL comes on it STAYS on until I reset it. Car drives fine, temps are low, etc...

Any direction would be greatly appreciated! With X-Mas coming I don't want to be chacing this with dollar bills in hand.

maf would affect both banks, wouldn't you agree?

Yes, My concern is how fast the CEL responds to a fault reading. Because it happens so infrequently my concern is that it just pushes the minimum and one O2 responds.

Not sure, but the idle is off @450 rpm. has a tendancy to begin stall and recovers, stalls and recovers, then smooths out.

Try replacing the o2 sensor...it's not that expensive....but your maf is probably bad they break very easily....i replaced the above and the engine still hesitates at idle especially while in gear..(atx) the engine light should not come back on and the engine should run a whole lot better.

I had teh same code come up on my tour, Then i used the SEARCH feature on this site and found advice on cleaning the MAF. It runs great now.

Often a MAF problem is nothing more than a dirty connection at the MAF sensor. The connection can be cleaned by removing and reinstalling the connector about half a dozen times. It also helps to smear some dielectric grease on the connections when they are apart.

I also agree that it is not likely to be the MAF if it is effecting only one bank. Possible, but not very likely. I think that it is likely that you will need to replace an oxygen sensor, especially if you found that it "flat lined" when scanned.

The check engine light will stay on until reset on OBD II cars. Yours is acting normal.

Most definitely try what you can before trying an oxygen sensor.

If you have a K&N type air filter, you may have a contaminated MAF sensor wire if the filter was over oiled. Cooked oil on the hot sensor wire can throw off the accuracy of the readings. Cleaning the sensor wire is worth trying, but often must be replaced. When this happens, you usually get MAF codes as well as O2 sensor codes, and again you would most likely get codes for both O2 sensors.

I've rambled a lot, but I hope I may have helped.