Public Service Message - AFTERMARKT O2 sensors SUCK!

[2Cool2Fool]

I have a 2007 Yukon 5.3 that was throwing a P-0420 code indicating that my catalytic converter was bad. After doing some online research, I checked the usual suspects: vacuum leak, MAF, air box issues, and PVC - all were good. I figured that the next best bet was possibly a faulty O2 sensor. Since the Bank 2 Sensor 2 was what the scanner indicated was the problem, I replaced all four O2 sensors with new Walker O2 sensors from Rock Auto. Within 20 miles of installing the new O2 sensors - the engine light came on - and the scanner showed the same Bank 2 #2 sensor was the problem.

At that point, I presumed that I actually had a bad catalytic converter - so I replaced it and re-installed the new Walker O2 sensors in the new cat. Sure enough - 10 miles later - engine light and the same P-0420 code. At that point, I was completely stumped. I told a buddy of mine (who is a GMC mechanic) about my problem. His first question was "What O2 sensors did you use?" When I told him i bought four new Walker aftermarket O2 sensors - he immediately said "That's your problem - Buy an OEM downstream sensor for Bank 2 and see if that helps". I went to a local GMC dealer and spent $85.00 on an OEM downstream sensor - and after installing it - it seemed to solve my problem. But after about a week, another Walker O2 sensors was throwing a code throwing an P-0420 code - but this time on bank #1. At this point, I decided to replace the other three O2 sensors with OEM GM sensors. Problem SOLVED. Haven't had a problem or and engine light in over 2,000 miles.

The bottom line: when you buy aftermarket O2 sensors - there is no telling what you're getting. Those Walker O2 sensor were total crap - and I probably wasted $700 on a cat that did not need to be replaced. From now on - ANY sensor that goes bad on any of my vehicles will be replaced with OEM sensors.

 

[Fless]

Moved you here from the General Discussion section.

It's been suggested over and over on this site to avoid aftermarket parts when Original Equipment is available. It's not Rock Auto that's the problem; it's the part manufacturer. Buy once, cry once.

 

[OR VietVet]

We preach and preach here to use OEM parts as much as possible. There are some valid substitutes but Walker sensors would not be a recommendation. I have used Walker exhaust systems for years with no problems.

 

[Joseph Garcia]

^^^^^x2^^^^^

You get what you pay for, AT BEST, but usually less.

 

[MWD_CTSV]

Denso manufactures the GM O2 sensors for your 2007 Yukon. I have used Denso 02 Sensors on many vehicles including my 2011 Yukon, without issue. I don't know anything about Walker sensors, but replacing all 4 sensors with the cheapest available without even doing any analysis of the OEM sensor readings is generally always going to lead to frustration.

Narrowband 02 sensors really only do one thing well and that is measure the presence of 02 or vice-versa not present, like an on-off switch. Very near stoich, the sensor voltage will fluctuate or switch across the boundary between O2 and no 02, such that near or at stoich can be reasonably deterministic, but it is NOT a linear measure of AFR.

The problem however is that the determining cat efficiency from that formula is not so good. You need to do more fudge factoring, which means that you need to account for the bias voltage and other minor errors of the sensor very carefully, because you have chosen the wrong sensor for the job. The OEM Yukon sensor was only used for 2006-2007 years, so perhaps it was problematic and quickly changed to another. It is also heavily shrouded giving a similar effect to those extenders which try to reduce the sensitivity of the downstream sensor to prevent a CE light.

So if anything it is that GM is too cheap in its cat monitoring, that it requires the unique faults and inefficiency of a specific sensor to try an extract a meaningful guess. In reality this compromise seems to work reasonably well, but it does require that the 02 sensor perform in a specific way when it is NOT measuring 02.

 

[donjetman]

07 Denail 6.2L
I changed all four of the original 175k mile working good O2 sensors with two GM genuine parts # 213-3533, $58ea, & two # 213-3538,$53ea - amazon 18 mths ago. .

 

[alpha_omega]

Funny that this became a topic of discussion. I recently asked @Doubeleive to update our “Daily Gen IV” thread with the info regarding some sensors he recently replaced. Primarily due to there being different boxes across the years and also differing upstream vs. down, as well as in the different brands used by OEM. We can toss a link in here if anyone needs the info/readout findings he provided.

 

[Doubeleive]

I have a 2007 Yukon 5.3 that was throwing a P-0420 code indicating that my catalytic converter was bad. After doing some online research, I checked the usual suspects: vacuum leak, MAF, air box issues, and PVC - all were good. I figured that the next best bet was possibly a faulty O2 sensor. Since the Bank 2 Sensor 2 was what the scanner indicated was the problem, I replaced all four O2 sensors with new Walker O2 sensors from Rock Auto. Within 20 miles of installing the new O2 sensors - the engine light came on - and the scanner showed the same Bank 2 #2 sensor was the problem.

At that point, I presumed that I actually had a bad catalytic converter - so I replaced it and re-installed the new Walker O2 sensors in the new cat. Sure enough - 10 miles later - engine light and the same P-0420 code. At that point, I was completely stumped. I told a buddy of mine (who is a GMC mechanic) about my problem. His first question was "What O2 sensors did you use?" When I told him i bought four new Walker aftermarket O2 sensors - he immediately said "That's your problem - Buy an OEM downstream sensor for Bank 2 and see if that helps". I went to a local GMC dealer and spent $85.00 on an OEM downstream sensor - and after installing it - it seemed to solve my problem. But after about a week, another Walker O2 sensors was throwing a code throwing an P-0420 code - but this time on bank #1. At this point, I decided to replace the other three O2 sensors with OEM GM sensors. Problem SOLVED. Haven't had a problem or and engine light in over 2,000 miles.

The bottom line: when you buy aftermarket O2 sensors - there is no telling what you're getting. Those Walker O2 sensor were total crap - and I probably wasted $700 on a cat that did not need to be replaced. From now on - ANY sensor that goes bad on any of my vehicles will be replaced with OEM sensors.

it should also be noted here that p0420 is bank 1 (drivers side), it's possible the code can "sometimes/rarely" be a out of spec 02 sensor, but I would hedge that bet on the age of each cat vs 02.

 

[2006Tahoe2WD]

I'm getting some O2 sensor P codes showing up so I'm looking at installing new.
RockAuto is confusing because it lists "Downstream" for pn 2133533 but that is an upstream sensor. Does anyone else see this?
Also, speaking of trying to buy GM OEM - if it says GM on RockAuto is that as good as buying at the dealer?

 

[Fless]

If the part is listed as "Genuine GM" on the RA site, it's THE GM part. I see two different styles of connectors for the O2 sensors, so you may need to look at what your truck has for connectors.

When you're looking at the RA parts, look at the specific INFO for the part and it will list some alternate part numbers:



If you use the gmpartsgiant site and enter your VIN, you can find OE part numbers there to match up with the RA alternate numbers. Here's what's shown for a 2006 Tahoe (you'll need to know which engine you have: LM7, L59, etc.):