O2 Sensors
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O2 Sensors
D17A2, 2001 Civic EX 1.7. P0135 and P0141 Codes. Mpg is down 5 miles per gallon and I notice now that the engine seems like it's in fast idle like my carbed 85 gmc s15.
Bought 2 Denso sensors for it, installed per directions, reset ECM and still have CEL.
I reset the ECM as per the shop manual, checked with a scanner and erased codes, codes returned in 5 seconds.
First, are Denso O2 sensors STAMPED in any way to tell if they are legit? Getting a sensor in a denso box means nothing sometimes.
Did the tests and am getting power to the sensor. Checked resistance and the manual says i should get 10-40 ohms, mine reads 5.2-6.0 so the manual says replace it.
The reason I mentioned the boxes is I bought these on ebay from an online parts store and want to verify that they didn't screw me over.
Second, another test said there was no ground from the pcm to the O2 sensor wire and I don't know if that affects the above and/or how to test if the pcm ground is working.
Any instruction on both questions would be very helpful because I now feel like I am going in circles and getting nowhere. Denso sensors 234-4122 (front) and 234-4621 (rear) are the p/n's.
Bought 2 Denso sensors for it, installed per directions, reset ECM and still have CEL.
I reset the ECM as per the shop manual, checked with a scanner and erased codes, codes returned in 5 seconds.
First, are Denso O2 sensors STAMPED in any way to tell if they are legit? Getting a sensor in a denso box means nothing sometimes.
Did the tests and am getting power to the sensor. Checked resistance and the manual says i should get 10-40 ohms, mine reads 5.2-6.0 so the manual says replace it.
The reason I mentioned the boxes is I bought these on ebay from an online parts store and want to verify that they didn't screw me over.
Second, another test said there was no ground from the pcm to the O2 sensor wire and I don't know if that affects the above and/or how to test if the pcm ground is working.
Any instruction on both questions would be very helpful because I now feel like I am going in circles and getting nowhere. Denso sensors 234-4122 (front) and 234-4621 (rear) are the p/n's.
Last edited by pullmyefinger; Feb 3, 2021 at 07:39 PM.
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Re: O2 Sensors
Strange you have codes for both sensors at once. If sensors are OEM replacement part, no shorts or opens in the circuits and no loose connections, then the PCM might be bad.
What exhaust or after market cold air intake?
Did you recently have a loose alternator bolt or alternator failure causing damage to the PCM?
What exhaust or after market cold air intake?
Did you recently have a loose alternator bolt or alternator failure causing damage to the PCM?
Last edited by NDNV; Feb 4, 2021 at 08:01 AM.
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No alternator damage that I know of. Nice to know that both codes being there is unusual. I need a document to tell me how to test grounds in the pcm and what else to look for. Thanks for the help!
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