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Discussion Starter · #1 ·
had exhaust system repaired and now have check engine light on indicating P0135. Investigated and found upstream oxygen sensor connector slides off male side with no effort, does not seem to fully engage. Does anyone know what the problem is? incorrect sensor? damaged connector. No problem before exhaust system repair.
 

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Discussion Starter · #3 ·
Either the retaining clip is damaged or missing due to repairs required removal of the sensor and person who worked on it damaged the connector or it is not being clipped properly due to debree inside preventing full engagement of the two halves mating together and causing the locking retaining clip not to engage or it is truly broken.
Thanks for the reply, slides apart with no effort or resistance from contacts. No debris on sensor end. Hand pressing two halves together does not increase engagement; engagement apart by less than .5 inch. If clip is broken, contacts should still engage. I found problem with two halves together so it was not free much time for contamination to enter. Even thought it might be upside down but not so. I think they installed incorrect sensor
 

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Discussion Starter · #5 ·
Then go back to the place that did the work and bring it up to their attention.
Sort of don't trust the place; check engine light was on and soon as I drove away. Paid $1049 for exhaust and catalytic converter. Fix one issue by end up with another.
Any problems with driving with upstream oxygen sensor disconnected?
 

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Discussion Starter · #7 ·
Then go back to the place that did the work and bring it up to their attention.
I called the place. Said there was no problem with that sensor. Waiting for his call back!

The place will install upstream oxygen that I purchase on ebay. Any good upstream oxygen sensor recommendations for 2005 Honda Accord LX with 2.4 4 cylinder engine. Door jam says the car meets federal emission standards
 

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Discussion Starter · #12 ·
when my upstream o2 sensor was disconnected, the error was p0135, why is the error code the same after reconnecting? doesn t the ecu know the difference between no sensor and faulty sensor
 

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Discussion Starter · #14 ·
The code P0135 means the heater circuit is not working, it does not mean the sensor is unplugged. The O2 sensor has a heater and a sensor, the heater brings up the temperature of the sensor quickly, so the sensor will work and go into closed loop faster. The sensor will heat up with the exhaust temperature but it takes a long time. If a sensor were to be unplugged you should get a P0134 code.

You can drive with a P0135 error it will take the car longer to go into closed loop operation.

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Thanks for your prompt response. The reason for my inquiry is that I had a cat converter and exhaust system repair a month ago. Right after repair, I had P0135 error. I found sensor not plugged in all the way until last week when i finally managed to snap connector together. Now after 200 miles, I have same error message. Never had P0134 error. Dont want to pay cost of replacing upstream oxygen sensor until I know old sensor is inoperable. Never had issue until CAT converter repair
 

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Discussion Starter · #16 ·
The heater is controlled by the ECM, the A/F sensor heater should have power all the time and the ECM grounds the heater to turn it on. That means the AF sensor heater has power all the time.

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So when unplugged, the oxygen sensor does not heat up because ecm cant ground it. One side is always 12 volts and the opposite side not grounded. ECM sees infinite resistance so the P0135 error.. Also when unplugged, the sensor portion provides zero volts to ecm.
 

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Discussion Starter · #18 ·
The way the ECM determines the heater is bad is that when it grounds the negative there is no current flow, also the sensor does not start working properly until it reaches 1200 degrees. There is no signal till the sensor is up to temperature.

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With cel on and after driving 200 miles, the only way to shut off check engine light is to replace sensor?
 
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