slang6

Hello,

I have a 2004 Honda Civic EX automatic. I currently have a check engine light on in my car(which is causing me to fail emissions testing), so i took it to the dealership and they say my PCM is bad. They claim that the voltage across the PCM is only 2.5 volts, the car is driving fine and no issues getting up to speed. the dealership gave me a quote of about 1K to fix, they say i need a new computer. From what I have read online it doesn't entirely sound like my entire computer is bad.

Any help would be much appreciated!! Also does anyone have a part number to see what i would need to replace, the dealership refuses to give me one for some reason.

thanks in advance!!

toyomatt84

iTrader: (1)

Get the codes scanned at a local auto parts store (AutoZone, PepBoys, etc...) and let us know what codes you're getting.

slang6

Ah yes sorry forgot to include that. I am getting code : P0134

toyomatt84

iTrader: (1)

Sounds like you've got a bad primary oxygen sensor.

slang6

So i just had the upstream O2 sensor replaced about 3 weeks ago. I had it replaced when I first started this adventure with my check engine light, since i had the P0134 code and another one - for the O2 sensor.

holmesnmanny

sounds like theyre saying the 5v reference going to the sensor is only getting 2.5

you can try sourcing a used ecu yourself

not sure if you got immobilizer

slang6

holmesnmanny

you're doing a test that would seem to confirm issue with the ecu https://www.rockauto.com/en/catalog/...computer),2896

fonkernuckle

iTrader: (5)

I would get a schematic to your car and see what pin on the ecu provides the voltage to that O2 sensor and use a t pin at the harness side and see if the expected voltage is coming out of the ecu with O2 plugged and unplugged.

slang6

Thank you everyone for the reply's, I appreciate the help. It turns out the mechanic who swapped my upstream O2 sensor put in the wrong part -__- . I personally installed the correct one this weekend and the check engine light is off!! I think the dealership was just making up the issue with the voltage being wrong, which doesn't surprise me as my car has been acting normally and not showing any computer related problems or common symptoms.