O2 Sensor Code Question (94 T-5)

[3-D]

i bought a 94 t-5 wagon this summer, and it was throwing codes for faulty/missing front and rear oxygen sensors, so he bougth a couple "tested" used ones at a junkyard to throw into the deal. i replaced the front one and reset the codebox. now i get just one code, 436 "maximum compensation rear o2 sensor".

my question is, does this mean the front sensor that i replaced is still bad or the rear one is bad? as in is the rear (functioning) sensor compensating for a bad front sensor, or is the rear sensor out of spec?

[3-D]

anyone? B)

[7 VII 7]

well looking that it says that the rear is bad from that code... looks like the rear is bad now :)

[AlvinL]

Could be since that was what you replaced but you could do some testing...

Code 4-3-6 (Rear HO2S Compensation)

1) Check for other codes. If Code 4-2-5 is stored, perform testing for that code first. If Code4-2-5 is not stored, go to next

step.

2) Perform a compression check on all cylinders. Repair as necessary. If compression is okay, go to next step.

3) Check for air leakage in intake system. Repair as necessary. If there is no air leakage in intake system, check for air leakage in exhaust system. Repair as necessary. If there is no air leakage in exhaust system, check fuel and residual pressure. Repair as necessary. If fuel and residual pressure are okay, go to next step.

4) Turn ignition on. Connect fuel pressure gauge to system. Squeeze hose between EVAP valve and intake manifold with Hose Pliers (115 8957). Code for EVAP system can be set. Start engine and run at idle until rear HO2S starts operating. Rear HO2S starts operating a short time after rear HO2S preheating starts.

5) Increase fuel pressure by squeezing hose after fuel pressure regulator with Hose Pliers (115 8957). Voltage across rear HO2S terminals should increase to about .8 volt. Remove hose pliers. Remove instrument cluster hose at intake manifold. If voltage across rear HO2S terminals drops to about zero volts, retest using new front HO2S. If voltage across rear HO2S terminals does not drop to about zero volts, retest using new rear HO2S.