Hi guys,

So for a while, my TSX has had the CEL flash on and off intermittently. The car had around 120,000 miles on it. Now, at 135,000, the CEL is on all the time. Reading the ODBII codes gave me error P0141, Sensor 1, Bank 2.

So I did some googling, and I was pretty sure that this was the "rear" o2 sensor (easy access under the vehicle). I ordered one of these.

http://cgi.ebay.com/ebaymotors/04-08...item2c53656415

It comes with a proper harness, an appropriate cable length, and it plugged in nicely in the sensor port located near the cat. I did notice there appeared to be another sensor in that vicinity..

After installing the part, I cleared the CEL (with my ODBII code reader, and by unplugging the battery after that failed) and it returned shortly after (within seconds). I get code P0141 again along with a new code, P1157. Googling tells me this is an air/fuel ratio error, probably something to do with the new O2.

At any rate, does anyone know which o2 sensor P0141 indicates? Are there two o2 sensors located underneath the car, near the cat? If so, does anyone have both part numbers? Otherwise, where is the third sensor located? This CEL is preventing me from getting registration tags, which are already 6 months out of date. Time to get crackin, I suppose.

Much appreciated!

 

Looking at the diagram, our cars have 2 sensors (19 and 20), one before the cat and one in the cat (I'll be honest, I've changed my oil 3 times since I bought the car and never looked). If you replaced the one in the cat there is a possibility that it could be bad but from what I have heard in the past it could be something wrong with the cat (although it is a rare issue from what I have read). What year is your car? You might want to have a dealer or someone look at it for you because a cat will run you about $500 for the part.

One other thing, when you installed the new sensor, did you use any anti-seize? If so you might want to pull it out and make sure none of it was accidentally placed on the actual sensor as it will cause problems as well.

 

P0141 is "Secondary HO2S (Sensor 2) Heater Circuit Malfunction". This sensor has to be disconnected from under the passenger seat, the harness is attached to the passenger seat rail under the carpet in front and the 4P connector is there too. Then the line is fed out the bottom and the sensor is replaced and the connector fed back under the seat. Looks like abourt a 2 foot lead from the sensor...and is located on the top edge of the cat. This may actually be a ECM/PCM failure too. the intermittent nature earlier suggests a loosening connection at either the sensor or the ECM/PCM.

P1157 is "A/F Sensor (Sensor 1) AFS Line High Voltage". This is the A/F Sensor, and also can be dues to a loose connection/failure at either the sensor or the ECM/PCM. The A/F sensor is located in front of the cat, right before the woven metal exhaust coupling. This 4P connector is in the open, so if you didn't disconnect anything inside the car, you didn't replace the HO2S Sensor

I would suggest you may have plugged a HO2S Sensor into the A/F Sensor hole. I say this because you described the location as "near the cat" rather than "on" the cat. Both sensors come with a 4P connector and a lengthy lead. That would explain the first CEL remaining and the new second CEL for the other sensor.

 

DuckDodgers: Thanks! I will switch them up and see what comes of it. Good thing I saved my old sensor!

 

According to that image, I changed part number 19.. But the stock sensor cable was much longer than the one in that image, and connected inside the engine bay. Is that diagram for a 2004 TSX 6-speed?

Thanks!

 

Hey guys. Just an update; I switched the two cat sensors around, reinstalled the one I'd removed, and CEL is gone.

Thanks for all your help!