Not another O2 Discussion!

bsa_m21 · Nov 12, 2017

Yup. Sorry. Searched all the old discussions but couldn't find a solution.

 My 96 D1 is throwing one code - P1193 - O2 Downstream Heater - Inferred Open Circuit Fault (one heater). I replaced all 4 sensors and cleared the code. Still throws it. So I swapped the downstream sensors from side to side. No change. Still just P1193. I've cleaned all the connectors and tried to ensure a tight connection.

I monitored it live in Torque Pro, graphing the voltages. What is really strange is that all 4 sensors seem to work for a while, then the Bank 2 one quits for a while, then starts up again. This is with the engine ECM in closed loop.

Torque Pro is also showing me the following failure:

TID $05 CID $01
Rich to Lean sensor switch time (calculated)
Min: 65,186
Test result value: 32,147
FAIL

I have no idea what this means, but assume it is related to the code.

Could the issue be somewhere between the sensor and the ECM, or in the ECM itself? If so, how do you go about determining which and fixing it?

I'd appreciate all thoughts.

M.

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discostew · Nov 12, 2017

I've seen the ECM loose its ground internally. Each sensor has a red/black wire going to it. That wire is just a ground even though it's going thru the ECM first. Get backprobed into that wire and when that sensor quits working ground the pin with a jumper wire.

If the sensor starts working with it grounded the cheap fix is just ground them all to the bracket the ECM mounts on. The truck doesn't seem to care that it's not doing the grounding.

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Not another O2 Discussion!

bsa_m21

Well-known member

discostew

Well-known member