2005 PCM O2 sensor Problem

2005 PCM O2 sensor Problem

Postby ESPTECH » Mon Oct 31, 2005 2:20 pm

Hello
Im hoping someone might be able to help me, or direct me to someone that can...

We recently installed a 2005 WRX engine, pcm, and wiring harness into a customers 2000 Imprezza RS. The engine runs great, and only has 1 fault code left. The code is a hard fault that comes back no matter what we do. The code that we get is P0031, this comes back as bank 1 sensor 1 heater circuit low input. We have verified all of the wires, purchased a new sensor, checked all of the connectors, and can not get the code to go away. From our testing, the pcm does not appear to be grounding the heater circuit like it should to turn it on. I visually inspected the pcm circuit board, and didnt see anything burnt or broken. Does anyone have any ideas besides buying a new pcm from Subaru? I have contacted pcm rebuild guys and they say it is too new... Any ideas???
THANKS
Karl
ESPTECH
 
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Postby cdvma » Mon Oct 31, 2005 6:46 pm

Is the harness ok? Have you checked for continuity between the sensor plug and the ECU?
cdvma
 
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Postby ESPTECH » Tue Nov 01, 2005 5:24 am

Yes, all of the wires have continuity from the plug to the ecu. All of the terminals seem tight enough. The ground terminals/wires from the pcm have good ground on the engine. The heater just doesn't get turned on by the pcm. We can turn the heater on by adding a ground wire to the circuit, but the internal volt meter does not see the load on the circuit and the corresponding voltage drop therefore we get the code.

Any other ideas?

Thanks
karl
ESPTECH
 
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Postby cdvma » Tue Nov 01, 2005 9:40 am

Dunno what to tell you except see if you can borrow another ECU before having to buy one. BTW if you want to buy a used one a guy under the username "Bill" on NASIOC might still have one from his wreck.
cdvma
 
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Postby megafrenzy » Thu Nov 03, 2005 3:40 pm

If the problem is on the ECU, try to follow the connection on the ECU board to whatever its hooked to. Use a meter to beep it out. Perhaps its a transistor that can be replaced or a relay. Maybe a cold solder joint or a bad via.

If you write down the part numbers, you can see what it is.
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