: Right oxygen sensor problem

Rob Benham
02-12-07, 02:57 PM
00 32 EGR open command did not change fuel mixture during off idle operation

00 63 Right oxygen sensor problem

I'm hoping that one is because of the other.

On the right side, very near to the exhaust manifold, 3/4 the way back, there is a unit screwed?? into the engine. It has clip on conector and only ONE wire going to it, but has two holes for wires, and the harness has been taped up on a previous repair.

Does anyone know A/ if this is the O2 sensor, and B/ if this should have two wires ( I can't see another wire down the sleeving ) but it could have dropped back.

Thanks Rob.

02-13-07, 01:28 PM
Pretty sure you are looking at the knock sensor. The KS is located in the engine block just above where the oil pan meets the block (and under the exhaust manifolds). There should only be ONE wire to the KS (there are actually two KSs, one in either side of the block).
Picture: http://shbox.com/1/ks.jpg and http://shbox.com/1/ks_2.jpg

The o2 sensor is located in the exhaust system (there are also two of these sensors and should be changed in tandem if money allows). AC Delco is the brand to use as many people have had issues with brands like Bosch and the like on these cars. Save yourself the trouble and money ahead of time and buy the more expensive Delcos the first time around.
>> The o2 sensor is located just after the exhaust manifold bolts up to the cat converter. The o2 is actually screwed into the cat converter pipes just in front of the "main" body of the cat itself. The sensor has a plug harness pigtail coming off of it and is about three or so inches in length. SOmetimes these are really stuck in there, and a specific socket wrench for o2s is helpful. You may need to drop the whole cat converter in order to be able to get at the o2 sensor and break it loose if frozen up badly.
Picture: http://shbox.com/1/ho2.jpg

Here is info on the EGR: http://shbox.com/1/4th_gen_EGR.html

Rob Benham
02-13-07, 01:42 PM
Hi again. I didn't see your post here until I had gone into hyper-ramble on my other thread!

Thanks for that. It's interesting about the special socket, I guess that is a must. Oh, and the cheap one I mentioned was Bosch............. Good timing on your part

The main point was

>>>>>>>>>I guess the question is, if I change the O2 sensor, is it possible that the EGR will spring back into life ?<<<<<<<<<<<<<<<<

02-14-07, 07:02 PM
In most cases one fault will cause others to pop up.

Don't go just replacing stuff, that is a sure way to waste lots of $$. Remember, unless contaminated, O2 sensors last a LONG LONG time. They have to, else they would become under serious scrutiny of the EPA. They do not fail in 30K miles like people preach. I am not saying they go bad, but I am betting that a lot of O2's hit the dumpster that are perfectly good.

The key is to get a tech tool/scan tool or datalogger and read the O2 sensor and ensure it is reading properly. There is no way to properly diagnose most any sensor on a car without actually READING it. Before I got a datalogger, I would connect up wires to the O2 directly and run it to my DVM and drive with it. At one time I had 4 multimeters in the car reading various sensors. It provided invaluable data.

Basically you need to prioritize the fail codes. What problem would cause the other failure, but not necessarily the other way around.

In this case, I would lean towards the O2 being the higher problem. BUT, did any other fault show up? If you clear the faults, do they return? Was the engine fully up to operating temperature? Is the engine GETTING up to full temp? What were the conditions that were occurring when the fault appeared?

O2's are actually far more resilient than people give them credit for. They key is warm enough. If the O2 heater is bad, this will also cause some numbing of the readings.

Try this, the best way to test the heater, is to let engine cool to where it is COLD, with the car up in the air on ramps. Then once COLD, turn ignition on and leave on, but do not start. After 5 min feel the O2's, they should physically be warm. If not, replace that one only. I DO highly recommend using GM sensors. I had a pair of non GM sensors in my 99 K2500 Suburban and I had lots of issues with them because GM spec's the sensor body must be grounded. The ones I have (Borg-Warner) do NOT meet that specification. I had to manually ground them to make them work. Now they are fine.

You can probably use an open end wrench to remove if you can get it on it. Ensure that the exhaust is COLD when you remove.

Rob Benham
02-15-07, 12:30 PM
Thanks NODIH, that's interesting on several counts.

Funny, but today it's freezing here in the south Texas ‘valley', it will be a good time to check on the heaters.

The other thing is grounding. Having turned it and tightened it again, the code didn't come back for a day or so. So, maybe grounding will be the answer.

I guess that there might be a voltage difference between the car ground and the case of the detector if there is a grounding problem. I'll check that as well. However, mine has 4 wires, so it might not need ground...I don't know how many wires the detection part needs.

EDIT. The 'good' O2 detector is hotter than the one that threw the code, but both are heating. I'm not able to get a DVM in there right now cos of having to stay clean, but I wouldn't be surprised if there was some resistance on the thread.

I managed to get an open ended wrench on the sensor and it turned with ease! but, without looking at a plug and seeing how to release it, I just couldn't get the connector apart. In fact with my aging bulk, I could just get my fingertips to it. If I could have popped it from the bracket it would be easier, but even that wouldn't come out without breaking it. Still, armed with your information it may not be necessary.

The key is to get a tech tool/scan tool or datalogger and read the O2 sensor and ensure it is reading properly. There is no way to properly diagnose most any sensor on a car without actually READING it. Before I got a datalogger, I would connect up wires to the O2 directly and run it to my DVM and drive with it.

That seems to say that you can read it from a diagnostics connection, is that the case?

I'm getting up to speed on the EGR system, and fault-finding seems fairly logical. It's just that this is not my finale choice of car and I was reluctant to do a degree course for such a short interval. But it's fun on a nice day...I have the image of you driving with the test gear on board, and I will never forget the post on connecting speakers to the SLS suspension to hear the square-wave input.

I'll get back on this, but I had better push the car out and check on those heaters.

By the way, I'm just negotiating for a Suburban ‘02 Z71 with 56k on it. Looks real nice but we're a bit apart on the price right now. Do you post on the Chevy forum ? I'm UK Texan on there.


02-15-07, 05:47 PM
I do, I am same screenname on FullSizeChevy.com, I don't go too much off the technical and performance forums. Pauly is the guru there, but I do frequent it, but it is far faster moving than this forum. You might get 50 threads in 2 hours there on Technical alone!

I'll post back in a bit... Gotta get to work!

Honestly most EGR failures are due to clogged passages and next is EGR diaphram failure. Note that this is a BACKPRESSURE EGR, so if the exhaust was changed, it can adversely affect the EGR timing (the times when it opens). The newer linear and digital EGR valves don't have this issue and the old Ported type. Positive backpressure EGR's are worse for it. Negative backpressure should be ok with it.