Did a scan and got this code. I have replaced the o2 sensor that is at the drivers side manifold,but I still get the code. It wants to stumble a little during idle when in drive,I guess because it's too rich. What should I be looking for? The scanner gives me some other info if needed. I just got this code after installing a Cold air kit I bought from a friend,could this be the culprit? I also have been told that a faulty Coolant temp sensor would cause this because it wouldn't go into closed loop mode?

 

This error code occurs when the O2 sensor passes the functional test, but repeatedly indicates the fuel mixture is too rich on one side (in the case, the driver side bank).

Any problem that would cause the PCM to be unable to properly control the fuel mixture on that side of the engine could be a culprit. A leaky fuel injector comes to mind. However, since this happened after installing a cold-air intake, I'd be tempted to check for damage to the MAF sensor.

I would also be tempted to put the factory intake system back on and see if the problem goes away.

 

I put the factory air duct back on and the ses light hasn't come back on yet. it still wants to stumble when the car warms up and it's in gear. How many 02sensors are in bank one. Like I mentioned I have already replaced the one at the manifold are there another one down stream?

 

Yes, on OBD2 cars (1996+), there is a second O2 sensor after the catalyst, on each side, but that sensor is ONLY used for evaluating the efficacy of the catalyst, and is not used in determining whether the air/fuel ratio is correct, or not.

Are you running a stock MAF sensor?

 

I don't really have the time to track down the culprit. I guess I'll take it to my repair guy on monday. why would it idle fine when cold,then start to idle rough when warm? Yes,it is a stock Maf. I have taken it off and cleaned it the other day to see if that helped. anyway to check it? So the other 02 sensor probably isn't my problem then?

 

If your scan tool can display the MAF reading while the engine is running, it would be interesting to know whether the readings are the same with the factory ducting versus your cold air kit.

The symptom you describe, where it runs fine when cold but starts idling rough when it warms up points strongly to a problematic sensor that is used for fuel calculations in closed loop mode (O2 sensor(s), possibly the MAF). I suspect something is funny with the MAF - it is sensitive and maybe it was damaged during cleaning or the installation of the cold air intake kit. You could try disconnecting it and see if the problem goes away. This will cause an SES light, but it will force the PCM to use "speed density" mode for calculating fuel mixture. I don't know off-hand if the MAF is used during open loop fuel calculations - if the PCM uses "speed density" mode during open loop this points even more strongly to the MAF.

There are a total of four O2 sensors on your vehicle, two on each bank. Only the "front" O2 sensors are used for fuel calculations. This code could not be caused by a failure of the rear O2 sensor.

Your post doesn't say whether you have custom PCM programming or not - do you?

 

No,my car is stock. Unplugged the MAF and it still idles rough.

 

Another possibility is that there is a problem with the new O2 sensor or the wiring to it. If the O2 sensor was misreporting its reading to the PCM, either because of a problem with it, or the wiring, the PCM would keep removing fuel from the driver's side bank until it went outside its range of control, thus tripping the code. If this was the case, the driver's side would be way too lean, which could cause your idle problem. To isolate this, I'd take a look at the spark plugs from the driver's side and compare them to the ones from the passenger side. If the driver's side is really too rich, the plugs will have carbon built up. If the driver's side is actually lean because of a problem with the O2 sensor, they will look very white, and possibly blued.

Also, if one or more of the spark plugs from the drivers side doesn't look like the other plugs from the drivers side (e.g. only one has carbon built up), this could mean that individual cylinder has a problem (e.g. leaky injector or mechanical problem). A compression test would track this down.

Maybe it is time to let your repair friend take a crack at it. ;-)

 

I was wondering if I may have gotten a bad(new) 02 sensor also. I think I may take it to the auto store and have it replaced and see what happens. I did look the drivers side plugs and the one I pulled had a white look to it.

 

Sounds like we're getting it narrowed down. Let us know what happens.

 

Simply switch the pre-cat O2 sensors from side to side. That will tell you if you got a faulty sensor, or contaminated it when you installed it (problem code follows the sensor).

You also need to look at the long term fuel corrections for both banks. The code sets when the PCM sees excessively negative long term (<-13.3%) and short term (<-9.4%) corrections. You may be able to determine if the problem is ONLY on Bank 1, or if Bank 2 is also experiencing the problem, but the long and short term corrections just haven't crossed the threshhold to set P0175. Something like the MAF is likely to produce problems on both banks. If its only on Bank 1, its got to be something that can only affect that Bank.

When the engine is cold, running in open loop, it uses the "learned" long term fuel corrections, meaning the PCM can only pull about 15% excess (or "false" excess) fuel out. The short terms are locked at 128. That may keep it running 1/2-way decent. When it goes into closed loop, it can make additional corrections (leaning) using the short term corrections, which are no longer locked at 128 (0%). That might explain why it runs poorer when hot, and may be indicating you have a "false" rich condition.

 

I took it to the local garage because my guy is on vacation. They hooked it up to there 20k machine and there Technical conclusion " There Is Too Much Fuel on That Side" Well,genious that would explain my rich condition on bank one code. My guy comes back tomorrow and he's going to take off the New 02 sensor and get it replaced and put the new one on for no charge. The next time I get the SES light on,I'll check the long/short values and see what they are. Would you be able to see anything wrong If I was to post some more parameters Injuneer?

 

Got my car from my Mechanic and he said that the MAP sensor wasn't working correctly and it had a vacuum leak. as of now,my car is running fine with no SES light. Could it be this simple? We'll see!!

 

That's great!

 

My opening answer was a vacuum leak. But you discovered it before I can offer it up. Since you have a stock config, it couldn't have been something like a bad computer tune, injector sizing, or adj. fuel pressure regulator. All items that plague the rest of us.

As my old auto-shop teach told us, always perform the visual inspection thoroughly before hooking up any of the test equipment.