I got a code P0171 on my 2003 Chevy Blazer. I know it is a O2 sensor, but where is it and could I get to it relative easy? I don't have tools like a professional mechanic but I have some. I know it is a matter of screwing the old one out, unplugging it and screwing in the new one and plugging it in.

 

Have a read through this:
P0171 - Fuel Trim System Lean Bank 1

It may or may not be an O2 sensor issue. You could have an exhaust leak before the O2 sensor on the driver side cylinder bank.

When was the last time you did a full tune up (plugs, wires, cap, and rotor)? How many miles do you have on your truck? If it is over 100,000 miles, then it may be time to replace the O2 sensors as they get lazy as they age.

 

A full tune up was done in April. It would not start in April so I was forced to do a tune up. My mileage is 61800. The light went out before I had it scanned.

 

Do you believe it is the O2 sensor it self or a exhaust leak?

 

There is no way I can tell through the internet... You have to diagnose the problem from your end. Do you hear an exhaust leak? Have you looked at the diagnostic chart linked to above?

 

If you do have to replace any 02 sensors some auto stores will loan you an 02 sensor socket set. You pay for it when you take it but they refund your money when you bring it back. Beware as sometimes they come right out and sometimes they are rusted in. I have had to use a torch to remove them and onetime when it came out ,it took the threads in the exhaust out with it. GRRRRRR.
The new ones come with anti sieze on them but I always put some extra on the threads. Just don't let any anti sieze get on the sensor.

 

Thanks Terry for your advice. That was much needed. swartlkk, where can I buy a maintance manual for a 2003 Chevy Blazer 4 door 4x4? I notice you mentioned that the O2 sensors get lazy after 100,000 miles, but this would be my third O2 sensor to be replaced and I only have 61,000 miles on it. Replaced first 2 years with 43,000 miles and second one 1.5 years ago with 49,000 miles on it. I eager to rule it a sensor because I hear no hissing and the way the light acts, it acts like it did before the other two got replaced.

And last question for any one. Would it be adviceable to replace more O2 sensors? Does any one have a diagram where all the O2 sensors are located on a 03 blazer and which other ones should be replaced with it?

 

You should be able to get at all of the O2 sensors on these trucks with a regular combination wrench. My question about O2 sensor replacements would be why did you replace them? If it was in an attempt to fix this code, then a proper diagnosis was not done. O2 sensors should not be replaced unless they are found to be faulty. Even a code specifically pointing at an O2 sensors performance should be verified by swapping sensors side to side.

The only sensors that should be replaced as any part of somewhat routine maintenance are the upstream sensors (those before the catalytic converter on your truck). Even then, they should be verified as being lazy before they get replaced unless you like throwing money away. On that note, I have found AC Delco O2 sensors to far outperform others (especially Bosch) available in the aftermarket. Do yourself a favor and only use AC Delco O2 sensors.

Go through the diagnostic chart. Look at everything on the driver side exhaust to make sure that there are no leaks between the engine and the O2 sensor which might allow free oxygen into the exhaust, skewing the results.

 

you can buy the haynes manual at autozone, it's one big kinda generic one for S-10s, sonomas, blazer, jimmy, bravada and isuzu hombres. It has no mention of oxygen sensors though. these books are kind of notorious for leaving out sensor information.

 

For what it's worth when my 01 Catera threw a p0171 code it ended up being the MAF sensor. I know my 98 Blazer has a MAF sensor, I would think that your Blazer would have one also. It may be worth trying to clean yours. There is a little wire that can get dirty. I bought a can of MAF sensor cleaner, I forget who makes it. It worked for a while
I did end up replacing the MAF sensor and I have not had the code again.
This is just a thought I like to try the easy stuff first.

Don