Jaxon2580

Hey guys,

When I did my header install and removed the cats I got the initial codesP0137 P0141 P0157 P0161 all of which are 02 sensor circuits low which I expected but after a week I'm getting P0138 which is rear 02 bank 1 circuit High and I notice my mileage got worse. It's supposed to be a rear 02 but I have none plugged in for the after cats so is it normal for this code? Thanks

Wolftrk99

iTrader: (5)

If the sensor is disconnected it will read full on reference voltage which inturn will give you a rich or voltage high code....short answer would be yes!!!

Jaxon2580

So I shouldn't worry about this code? Just wondering because I figured 02 sensors create their own voltage and don't use a reference voltage so its just odd that a circuit that isn't plugged in is getting a high voltage

Wolftrk99

iTrader: (5)

Get them tuned out

Suburbazine

O2S uses 450mv reference voltage from the PCM and they switch from high to low states (boost or reduce this voltage) depending on the oxygen potential difference between the reference in their core and what is passing through the exhaust. In the case of a disconnected rear O2S the most likely cause is water in the connector during start-up causing 12vdc for the heater to reach the signal pins.