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For months now I've been trying to figure out how to get my 2003 EX coupe's engine to stop bogging down on acceleration when the engine is cold. I've read about this problem all over the net on forums and blogs and I've never seen a conclusive solution to any of them. Along with the uneven engine performance, I've been getting the CEL intermittently on and off, each time giving the code P0132 (O2 Sensor Circuit High Voltage [Bank 1 Sensor 1]). I read up on what to do and I got only two things: a) check the wiring. Uh, yeah. They look like wires. All the connections that I can see look fine and seem solid. 'Kay. b) change the sensor. Ok, so I bought one of those Bosch universal sensors that claims to be the best all over the place. I had to splice the original connector (this is the sensor before the cat, btw) with the connection kit the Bosch came with, the wire colors matched perfectly and I followed the instructions to the letter. No change. Still throwing the same code, same engine problems. I talked to the dealer a little, but they were just, "bring it in or buy the parts from us." Naturally.

So I bought a Denso sensor from some "Parts Train" website and it claimed to be an OE part (I even pried the brand name of the manufacturer's parts out of the dealership guy and he said Denso). Odd thing was, the connector that was attached to the Denso (I really didn't want to splice it again) was a male and the original connector that was on the old sensor I took off was a female. Wtf? If it's suppose to be the "actual" part, why would the connectors be different? The original and the new connectors fit perfectly into each other! Also, the wires were different colors, but they matched sensibly when I plugged them into each other-- original: two blacks, one white, one gray; denso: two whites, one black, one blue. They matched in that order, so i used the connector kit again, attached the old connector and installed it. As soon as I turned on the engine I noticed the difference! No rough idling, I could hold the accelerator at around 2000rpms and it would stay even (not dropping, sputtering, and sometimes stalling like it used to), and taking off from zero mph was smooth and quick. I was quite happy.

Then after about 5 mins into my test drive, the CEL comes on again. I pull over and read the code and it's showing the SAME DAMN P0132 code along with a P0420 (Catalyst System Efficiency Below Threshold [Bank 1])! Somewhat exasperated, I deleted both codes just to see if they would come back, you know, what the hell. They did, in just a few minutes. Same codes. I read up on P0420 and most everyone says, "just change the cat".

Does anyone know just what the hell "O2 Sensor Circuit High Voltage" would indicate and any ideas on how to make it stop? Also, if I have to change the catalytic converter, is it something I can do myself? I was reading some repair manuals and they made it sound like the EX model's cat is not built into the exhaust system and can be removed with a few bolts. Is that accurate? I'm just waiting on my tax refund to start on this because, otherwise, I couldn't afford it. I'm stuck driving my old truck which uses at least twice as much gas. I live in California and no one sells CA-legal cats except the dealer. They want $940 for one. I just would like to know what I could be getting into. Thanks for reading!

 
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bought one of those Bosch universal sensors that claims to be the best all over the place. I had to splice the original connector (this is the sensor before the cat, btw) with the connection kit the Bosch came with, the wire colors matched perfectly and I followed the instructions to the letter

MMMM well I know this. That sensor is a wideband O2 sensor so that could be a reason.