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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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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.
 

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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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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
Then go back to the place that did the work and bring it up to their attention.
 

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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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Short term: increased fuel consumption.
Long term: catalytic converter 0lus plethora of other possible issues , of course oxygen sensors.
Going back to the shop to have issues corrected under warranty on work and parts should not be a thing to question.
 

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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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Buy genuine sensors, avoid at all costs eBay and Amazon generic sensors and even those for sale as a good brand name maybe counterfeits on those online shops. Find out what brand of the sensor was the OEM for your vehicle. Denso or NTK. I only used Denso brand sensors for all my vehicles.
 

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There's probably nothing wrong with the sensor. They broke the plastic clip on your car's harness. This happens with aged plastic. Zip tie or electrical tape it back in place. I've broken many plastic clips in my days. They just get old and brittle.

I have a 1972 Ford truck and holy moly the plastic in that thing is like dust sometimes.
 

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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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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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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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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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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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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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If 12v is at the pins for the heater, and the return connection is at the ECM and the heater is not drawing current. Then the heater is bad, but it is not a separate part it is built in to the sensor.


Here is how to test, you can test with a simple test light to see the ECM turn on and off the heater. Then check the heater circuit for resistance to prove it is bad.



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