Thyme
New Member
- Joined
- Jun 2, 2022
- Messages
- 32
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- 15
Hey all, I'm having a real headscratcher of a problem with my Bank 2 Upstream O2 sensor. It failed on me out of the blue on a long trip across the country, or so the ECU claims. Its a Bosch O2 sensor, put in the car at the same time as the other functioning upstream O2 (also Bosch).
When the issue is happening, the ECU seems to be reading the sensor voltage as ~0.09-0.11V, or 0V. It'll throw codes for both a failed heater circuit and a failed O2 sensor. I attempted to solve the issue with another O2 sensor, which lead to the same problem. I then replaced the plug on the harness, as I saw the sheathing for the wires near it was damaged. Verified my wiring job and tested continuity on all wires from the sensor to the harness plug near the battery. Heater circuit read 5 ohms on both sensors at both the sensor connector and the harness near the battery, and I was able to see voltage from both sensors when heated with a torch and probed by a multimeter. The only place I haven't checked at is the connector at the ECU itself, as I'm a bit too lazy to dig the thing out at the moment.
The strangest part is this log I took using Forscan (https://files.catbox.moe/cllvrf.fsl). It shows the O2 sensor reading fine, and then suddenly starting to drop off down to the previous voltage range I mentioned before. I've seen this behavior on startup with a cheap OBDII reader viewing live data as well.
Any clues as to what could be screwing up on the car?
When the issue is happening, the ECU seems to be reading the sensor voltage as ~0.09-0.11V, or 0V. It'll throw codes for both a failed heater circuit and a failed O2 sensor. I attempted to solve the issue with another O2 sensor, which lead to the same problem. I then replaced the plug on the harness, as I saw the sheathing for the wires near it was damaged. Verified my wiring job and tested continuity on all wires from the sensor to the harness plug near the battery. Heater circuit read 5 ohms on both sensors at both the sensor connector and the harness near the battery, and I was able to see voltage from both sensors when heated with a torch and probed by a multimeter. The only place I haven't checked at is the connector at the ECU itself, as I'm a bit too lazy to dig the thing out at the moment.
The strangest part is this log I took using Forscan (https://files.catbox.moe/cllvrf.fsl). It shows the O2 sensor reading fine, and then suddenly starting to drop off down to the previous voltage range I mentioned before. I've seen this behavior on startup with a cheap OBDII reader viewing live data as well.
Any clues as to what could be screwing up on the car?