Hi, My check engine light came on again a few weeks after I thought I got the problem of my Evac leaks taken care of. This time it is throwing a new code: P0138 1/2 O2S Shorted To Voltage. Does anyone know what this means?? Or what I need to do to fix it? It sounds like there is a problem with my up stream o2 sensor??? Thanks in advance for any help!!

 

The 1/2 means bank 1 sensor 2, which also means the post o2 aka the downstream sensor. The wiring is shorted or the sensors bad.

Check the wiring and the harness for damaged wires. Also clear the code and see if it comes back. If it does, replace the sensor and/or wiring.

 

1/2 oxygen sensor is actually a downstream oxygen sensor.....(also called post catalyst) First, you might want to check the wiring at the oxygen sensor. 1/2 sensor means Bank 1 Sensor 2......Bank 1 is the side where #1 cylinder is & Sensor 2 is the second sensor on that bank (Downstream). Hope this helps!

 

California emissions?

 

Make sure wires did not get burned on exhaust system.

 

ok great thanks for your help! Also I recently had my cat removed but modified the downstream sensor so that it shouldn't read no cat. Could this be causing the problem too?

 

nah.. you've got a short... i bet a dollar you bent a blade in the connector, or introduced mud or something..

did you use the non-fouler trick?

 

If it is showing shorted, I would assume that the PCM is seeeing 0 volts. It expects voltage and expects it to constantly vary. (Am I correct on this drew?)

 

you tell me HOW you modified your downstream sensor and i'll tell you if it could be causing the problem.