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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29494
Experience:  GM Grand Master Technician 2007. 14 years experience.
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I'm reading the 2003 Tahoe O2 sensor thread. My check engine

Customer Question

Customer: Hello, My name is ***** ***** I'm reading the 2003 Tahoe O2 sensor thread. My check engine light is on and it is throwing 4 codes. I will check the fuses tonight after work.
JA: Thanks. Can you give me any more details about your issue?
Customer: I was having "Reduce Engine Power" issues and the mechanic replaced the computer. Didn't end up being the problem, I watched a youtube video and fixed the rear engine ground in my driveway which solved the problem. Upon the replacement of the computer the Tahoe was throwing all 4 O2 codes (Will post them after work) and the mechanic said it was just coincidence. However, he had the entire fuse block tore apart trying to fix the "Higher than normal voltage issue" that he said was the computer. In summary, I believe that he had something to do with the sensors and it may be the fuse or something did not get hooked back up. Thanks for the help!
JA: OK got it. Last thing — JustAnswer charges a fee (generally around $18) to post your type of question to Chevy Experts (you only pay if satisfied). There are a couple customers ahead of you. We can help you for less if you're not in a rush. Are you willing to wait a bit?
Customer: Sure. I will not be able to check on the codes or fuses until after work.
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Submitted: 1 year ago.
Category: Chevy
Expert:  GM Tech (Cam) replied 1 year ago.

Hi there, I am Cam.

Hanns, do you have the exact code numbers please?

Customer: replied 1 year ago.
Ill get them this afternoon. I'm at work.
Expert:  GM Tech (Cam) replied 1 year ago.

Perfect Hanns, have a great day in the meantime.

Customer: replied 1 year ago.
Hello Cam,
The codes are: P0135, P0141, P0155, P0161. Did I mention that the last mechanic had the fuse block completely disassembled. Could be coincidence though.
Expert:  GM Tech (Cam) replied 1 year ago.

Those 4 codes are for heated oxygen sensors, one for each. AT each injector, do you have power on the pink wire?

This may be related. The fuses O2A and O2B in the underhood fuse block feed power to all sensors.

Customer: replied 1 year ago.
I'll have to check for power on pink wires probably tomorrow night after work. So I check at each injector? Running or not? Anything else I could check this weekend? Are you on here on Saturday?Thanks.
Expert:  GM Tech (Cam) replied 1 year ago.

The second VIN has the 65E, so stronger.

Customer: replied 1 year ago.
I think your last message was meant for someone else?
Expert:  GM Tech (Cam) replied 1 year ago.

Shoot, yes. Computer issues, Sorry Hanns. Saturday I will be around.

This is tested at each oxygen sensor not injector. Key on, engine off is ok.

Customer: replied 1 year ago.
I dont have a pink wire. 2-black a white and a blue? which one should I test?
Customer: replied 1 year ago.
I have power to the fuses and their not blown.
Customer: replied 1 year ago.
ok, there is power to both blacks on all four sensors.
Expert:  GM Tech (Cam) replied 1 year ago.

Ok, is there any wiring issues as these return to the PCM?

Customer: replied 1 year ago.
I don't see any wiring issues. Who is the OE manufacturer? should I replace the two rears (they look easier) and see if the codes back? Thanks, Hanns.
Expert:  GM Tech (Cam) replied 1 year ago.

OE is GM/AC Delco.
They are common for issue, but check the wiring closely to them.