I'm lost here, please help

[Juanmiguel]

So I still have problems with the O2 sensors:

I first got a code and it kept coming back after a couple of days when I deleted them. I decided to buy a new duralast sensor. When I installed it, car would run like crap and on powrtuner it would read 1106 mv all the time even with the car turned off. I went and changed the sensor for another duralast and the same thing happened, so I took my money back and kept my old sensor.

Next, I bought a Tomco O2 sensor, installed it and now I get a P0134 (not enough activity), the scanner readings are either 437 and 451 (I get the exact same readings with the sensor disconnected) I only get these two no matter how much i accelerate and with the engine turned off. The trims are also 0% all the time now.

Problem is that now the same thing happens with my old o2 sensor, but it was reading in the 400's and wouldn't go any higher or lower except this one would read different values, not just two like the new one. On the way home just now, the old O2 sensor starting reading only 2 values also, but this time is 0 and 4 mv.

When I have no O2 sensor connected the O2 readings are also 437 and 451 always, but I'm not sure if this is right, I thought it should read 0 mv with the sensor disconnected.

I also tried using a different PCM and nothing changes. I tested the wires for connectivity from the sensor connector and the pcm connector with a multimeter and they seem to be ok.

Now my question is what should the O2 reading be with the sensor disconnected? I'm not sure what to do next, should I go and get a 4th sensor and test it? Maybe a bosch one this time?

Perhaps try a 3rd PCM?

[Bob Padilla]

So I still have problems with the O2 sensors:

I first got a code and it kept coming back after a couple of days when I deleted them. I decided to buy a new duralast sensor. When I installed it, car would run like crap and on powrtuner it would read 1106 mv all the time even with the car turned off. I went and changed the sensor for another duralast and the same thing happened, so I took my money back and kept my old sensor.

Next, I bought a Tomco O2 sensor, installed it and now I get a P0134 (not enough activity), the scanner readings are either 437 and 451 (I get the exact same readings with the sensor disconnected) I only get these two no matter how much i accelerate and with the engine turned off. The trims are also 0% all the time now.

Problem is that now the same thing happens with my old o2 sensor, but it was reading in the 400's and wouldn't go any higher or lower except this one would read different values, not just two like the new one. On the way home just now, the old O2 sensor starting reading only 2 values also, but this time is 0 and 4 mv.

When I have no O2 sensor connected the O2 readings are also 437 and 451 always, but I'm not sure if this is right, I thought it should read 0 mv with the sensor disconnected.

I also tried using a different PCM and nothing changes. I tested the wires for connectivity from the sensor connector and the pcm connector with a multimeter and they seem to be ok.

Now my question is what should the O2 reading be with the sensor disconnected? I'm not sure what to do next, should I go and get a 4th sensor and test it? Maybe a bosch one this time?

Perhaps try a 3rd PCM?

Denso 02 sensor from rock auto,try that since the bosch ones have a high fail rate on our cars. Most low end (readily available) 02 sensors die quick. Hope this helps.

[Bedwards]

From what I remember, when I had the O2 sensor disconnected, it read mid 400's constantly.

[Juanmiguel]

From what I remember, when I had the O2 sensor disconnected, it read mid 400's constantly.

Thanks for the info, that means my readings aren't wrong. I just find it hard to believe that I've got 3 defective sensors in a row. I think I'll order a Denso one from rockauto.

[Juanmiguel]

Just an update here in case anyone wants to know for future reference. Yesterday my powrtuner wouldn't connect anymore. After some testing I found out that the serial cable had two pins that had no connectivity from end to end.

I'm thinking the issue may be related with the tuner. When I actually took out the old pcm and connected it, it would read O2s normally, but after I reprogrammed it, it wouldn't read them anymore. At that point I thought maybe it was because the engine was cold or something and discarded it as I couldn't reproduce it.

I'm guessing that this cable was defective while I did the last tune, but the powrtuner program didn't pick it up.

I'm getting a new serial cable and will try to do a full write on the PCMs and hope they are not completely fried. If not I'll pick up another one.

[Juanmiguel]

ok I ordered a denso O2 sensor from rockauto and just installed it, it works fine now, all readings are correct.

So I DID happen to buy 3 defective sensors in a row....