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P1130 O2 Sensor Voltage Issue on 1999 Ford Taurus 24 Valve - Fixed Zero Reading After Repair

Model: 1999 Taurus 24 Valve Fault Code: P1131 Posted: 2015-08-14 13:28

I'm experiencing a persistent P1131 fault code on my 1999 Ford Taurus with the 24-valve engine. My OB2 scanner shows a fixed zero voltage reading from O2 Sensor 1 (Bank 1, Sensor 1), despite the vehicle running smoothly. I've already replaced the oxygen sensor, but the issue remains unchanged. The code did not appear prior to the transmission rebuild, which raises suspicion about potential wiring damage during that service. I suspect the problem may be related to damaged or disconnected wiring. Any insights into possible causes or diagnostic steps would be greatly appreciated.

Related fault codes
P1131
Comments (5)
Anonymous 2015-08-14 14:09

You're reading data from the correct sensor—Bank 1, Sensor 1. I suspect the issue might stem from damaged wiring. Check for any pinched, frayed, or disconnected wires, especially those that may have been affected during the transmission rebuild process.

Anonymous 2015-08-14 14:41

No, it's definitely Bank 1 Sensor 1. The only thing I haven't tried yet is verifying if there's a reference voltage present at the sensor. I've already inspected all wiring and found no visible damage. My transmission mechanic is going to blame this P1131 code on me and insist it needs fixing—thanks for the tip though.

Anonymous 2015-08-15 15:15

After inspecting under the hood, I discovered that removing the PVC valve and breaking its vacuum connection restored normal operation. At that point, O2 Sensor 1 (Bank 1) began showing a proper voltage reading. However, after the car warmed up and ran for some time, the voltage returned to zero—any ideas on why this might happen again?

Anonymous 2015-08-21 10:45

This vehicle seems cursed! After finally diagnosing the P1131 issue, I found it was actually a faulty oxygen sensor. Now I'm getting a new code: P1100—related to the Mass Airflow (MAF) sensor. My transmission mechanic won't touch the car until these emission-related issues are resolved. Lesson learned: don't ignore O2 sensor problems after a transmission rebuild.

Anonymous 2015-08-21 12:27

Clear the P1131 code and monitor if it returns—this will help confirm whether the issue is intermittent or persistent. The P1100 code indicates an MAF sensor problem, which is typically a wiring-related fault. Start by cleaning the MAF sensor (even though this won't fix wiring issues), inspect the connector for tightness and corrosion, and check the first few inches of the harness—this area often fails. If none of these steps resolve it, a digital multimeter (DVOM) will be necessary to perform further diagnostics.