This past weekend I put a new clutch/flywheel in my car, no issues at all. As soon as I started it up the CEL came on, I expected this because I had my test pipe removed to make sure it would actually run right before buttoning it all back together. The first code I saw was a Secondary Air code, after clearing the code it never came back. The second code keeps coming back immediately after start up, a P0141 (O2 Sensor Heater Circuit Malfunction, Bank 1 Sensor 2). I replaced the O2 sensor that goes in to the catalyst, however the code popped up again immediately. Is it possible this code is meant for Sensor 1, before the catalyst? I had crimped one of the harnesses that goes to the transmission area of the car when I went to pull the transmission off, but I quickly realized it and moved the harness. Is it possible that the wires in the loom for the O2 sensor got crimped and are damaged? The car runs great as you would imagine, but I am not a fan of CEL's by any means (I mean who really is).

Any help is appreciated. Thank you guys in advanced.

 

Is it possible the o2 sensors are reversed

 

I have had the exact same issue and haven't been able to track down the problem. That said I haven't tried too hard as the secondary O2 doesn't do much. Be sure to update with what you find.

 

I thought the same but everyone keeps saying the connectors are different. I'm putting the car back on the lift tonight when I get home to confirm that.

 

same happened to me.

reversed the wires... still same issue.

i'm gonna take another look at it again soon.

 

is it possible the 02 sensors are in the wrong location?

 

o2 sensors are different. one is male and one is female, so it should not be possible to mix them up.

 

The o2 sensors can be mixed up, only if they are completely unscrewed from the cat and header. The cable lengths are adequate.

If the sensors themselves were never unscrewed, then the wires cannot be mixed up. However, In this same scenario, the o2 sensors can be plugged into each other.
The ECU connectors can also be plugged into each other. Even a momentary mis-connection with the key on can fry the heater circuit in the ECU.

Color designates position depending on year, what year car?

 

Maybe i'm not understanding which wires people are supposedly able to reverse, but at least for 2003 AP1, the primary/upstream O2 is male (sensor side) and the secondary/downstream O2 is female (sensor side). So they shouldn't be able to be reversed.

Primary/Upstream male Denso p/n 234-4124




Secondary/Downstream Female Denso p/n: 234-4601

 

Look at your pictures then imagine both those plugs connected together, yes it works
Same thing for the engine side connectors and this will most likely fry your ecu.