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simo10 12-04-2012 11:54 AM

P0041 and P0123
My girlfriends car is throwing these two codes.

Check Engine Light Code P0041

Downstream O2 Sensors Swapped Bank To Bank

P0123 Code - Throttle Position Sensor/Switch A Circuit High Input

It's a stock 02 Focus, SPI engine, 5 speed manual. 151,xxx miles

It seems to run ok, minus some vibrations (mounts are new) and the speedometer sometimes decides to quit.

Any idea what could cause these codes, especially P0041? I can't find much info on it. I have never touched the oxygen sensor wiring and it didn't used to have this code.

simo10 12-07-2012 08:06 PM


freemind 12-07-2012 09:54 PM

Clear the codes and see if they come back.

Then we will talk about replacing stuff.

simo10 12-08-2012 02:55 PM

What is the proper procedure for this? oi unplugged the battery for 10 min and it came back withing a few days.

BC_ZX3 12-09-2012 10:11 AM

Your P0041 code is non-sensical because the 4 cylinder Focus only has a single bank of cylinders (V6s and V8s have two). It may be indicative of a wiring harness short. The only way to tell is to do a visual inspection of the downstream O2 sensor connectors and wires.

If the speedo sometimes quits as well it would be suggesting you have an electrical short somewhere.

If the DTC codes reappear, the problem is persistent. Your method of clearing the codes is correct, although using a proper OBDII code scanning device would be better.

simo10 12-09-2012 01:43 PM

All O2 connections seem solid, although the connector for the downstream sensor is kind of floating around and very close to the axle. I couldn't see anything out of the ordinary.

Could it be a bad O2 sensor?

BC_ZX3 12-09-2012 08:39 PM

An internal short in the O2 sensor is possible although not probable.
Simply disconnect the rear O2 sensor harness connector, wire it up out of the way, clear your DTC codes and see what codes (other than P0420) appear. If your P0041 fails to reappear, the O2 sensor needs replacement. If P0041 reappears, the O2 sensor is not the problem source.
Are you in a hatchback or a sedan?

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