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Mike V.
Mike V., Auto Service Technician
Category: Car
Satisfied Customers: 24022
Experience:  25 years of experience, Certified Subaru Technician and Nissan factory trained.
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2001 rodeo V6. Shows codes o2 sensors and speed sensor.

Customer Question

2001 rodeo V6. Shows codes for bad o2 sensors and speed sensor. Replaced and still have lights. Further testing shows no ground to o2 sensors, but engine ground is good. Bad computer? Help.
Submitted: 1 year ago.
Category: Car
Expert:  Mike V. replied 1 year ago.

Hi there,

According to the wiring diagram this does indicate an issue with the computer or the harness connectors going to the computer. If you have lost ground to all 4 sensors this would have to be the problem.

Expert:  Mike V. replied 1 year ago.

If you have the specific codes I may be able to confirm this a little better as it looks like the grounds are for the heater circuits on the sensors. The speed sensor code is not likely the same issue however.

Customer: replied 1 year ago.
Don't understand your first reply. You said "this would have to be the problem" What is "this", the computer? It does show no ground to any of the sensors. Sorry don't have the codes here with me.
Expert:  Mike V. replied 1 year ago.

Sorry, the computer you were asking about. These are all grounded via the pcm on the truck.

Customer: replied 1 year ago.
if all O2 sensors are new and none show as grounded, then I have a bad computer, correct?
Expert:  Mike V. replied 1 year ago.

How are you testing for ground? Each sensor has it's own individual wire for grounding the sensor. So, if you are using a meter and checking for continuity to ground and don't have any, this is correct.

Customer: replied 1 year ago.
Actually the code reader used indicated no ground for any of the sensors, so it was saying the ground through the computer was bad. Just didn't want to replace the computer if it wasn't the problem.
Expert:  Mike V. replied 1 year ago.

Well, Best I can do without any codes is to tel you there are wires for the grounds that run to the computer on the truck. If its not getting any ground at all, it seems most likely the issue would be there then on 4 separate wires.

Customer: replied 1 year ago.
Could the ECM relay possibly be the problem. Does it provide power or ground to the ECM?
Expert:  Mike V. replied 1 year ago.

The ecm relay supplies power to the ecm. If you can read codes from the ecm, it's coming on.

Customer: replied 1 year ago.
Thanks for you help. I had thought it was the computer, just needed a little more information to be sure.
Expert:  Mike V. replied 1 year ago.

You are very welcome, please let me know if there is any more I can do, and please remember to rate my answer.

Thanks so much.

Customer: replied 1 year ago.
One last question. Is it necessary to have the replacement computer reprogramed by the dealer?
Expert:  Mike V. replied 1 year ago.

According to my info it will have to be reprogrammed. I would contact a couple of independents to see if they have the info to reprogram it. It is likely dealer only, but it's worth a phone call.