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I replaced my PCM. It is throwing P0138 which is a sensor high voltage on the downstream right side.


I checked ground lines for all the sensors and they are good. I have replaced all of the sensors with new bosch ones.

Is it just a garbage bosch o2 sensor and should I just replace it with an OEM one?
 

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Checking the ground lines for all the sensors and finding them to be good verifies the ground circuits for all the sensor heaters are good.

P0138 requires troubleshooting the signal circuit and signal return circuit for the right side lower O2 sensor. (Right side as viewed from behind the engine.)

Here is where you should be looking:

Possible Causes

O2 1/2 SIGNAL CIRCUIT SHORTED TO VOLTAGE

O2 RETURN DOWNSTREAM CIRCUIT SHORTED TO VOLTAGE

O2 1/2 SENSOR SIGNAL CIRCUIT OPEN

O2 RETURN DOWNSTREAM CIRCUIT OPEN

1/2 O2 SENSOR

POWERTRAIN CONTROL MODULE (PCM)
 

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Turned out to be the sensor. Which it is about 99.999 percent of the time.

The Bosch one I got was garbage.

The NTK one I got also turned out to be defective.

I swapped the sensor to the other side and the code followed. Put an old sensor in that I knew worked but had a blown heater and the code cleared out.

Got a second NTK and everything is great now.

This drove me nuts for a week, I built test plugs to trace the lines, pulled the PCM and swapped it with another. And it was just 2 bad sensors in a row. Time for Mud and cold beers. In that order.
 
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