P0131 Ford 3.0L – Test Ford Escape 02 Sensor

The P0131 Ford OBDII check engine trouble code in your 2001-2007 Ford Escape means that there’s an issue with your primary oxygen sensor. If your Ford check engine light is preventing you from passing your emissions test, you can use this simple guide to test your Ford Escape oxygen sensor (02 Sensor). This specific OBDII trouble code is classified as Upstream Heated Oxygen Sensor Out of Range (Bank 1, Sensor 1).

The heater wire in your Ford helps the oxygen sensor read and analyze your the contents of your exhaust gases. Transmitting the oxygen and fuel readings directly to your Escape ECU, the P0131 Ford check engine light can cause engine issues as well your overall decrease gas mileage. I’ll be showing you how to test the range of your oxygen sensor circuit in your upstream 02 on a 2004 Ford Escape XLT with a 3.0 liter engine in it.


As the Bank 1 Sensor 1 oxygen sensor, this is for the pre-cat sensor that is responsible for fuel injection function. This sensor can also be recognized by your scan tool as O2S11, and if the code in your Ford scan tool reads O2S21 that is for the Bank 1, Sensor 2 OBDII trouble code P0420. Because this P0131 Ford trouble code is for Sensor 1, this is for the side of your 3.0 liter Escape engine that has cylinders 1,2 and 3.


P0131 troubleshooting can be performed using a Ford compatible scan tool that can display real time engine values known as Live Data. By scanning the fields or PID’s within your scan tool for the relevant data, you can accurately gauge to see if your oxygen sensor has gone bad.

How to test your Ford Escape oxygen sensor voltage


Before you plug your OBDII scan tool into your Escape to read the PID in question, you must get your Ford ready for the testing procedure. Before you begin testing your 02 sensor voltage, follow these steps.

  1. Start the engine and allow the engine to warm up. Make sure you are in a properly ventilated area and not parked indoors or in a garage.
  2. Connect your OBDII scan tool and sync with your Ford PCM
  3. Scroll to the Live Data section
  4. Monitor the PID O2S11 for the value being transmitted by the upstream 02.
  5. Wait until your 02 voltage begins to “cycle” or oscillate in voltage between .100 and .900 volts

If your oxygen sensor does not cycle or pegs at .900 voltage or above, chances are you will need to replace your front oxygen sensor to correct your trouble code. You can also have a friend drive as you monitor these PID’s in real time. Remember while you are stopped at idle and the engine is warm, your O2S11 value should cycle.


Excessive voltage at cruising conditions is one of the most common issues that trigger this P0131 OBDII trouble code. Remember that sensor 1 is on the side of your Escape engine that houses cylinder 1, 2 and 3. Unplug the upstream oxygen sensor when your engine has cooled down.

Remove your Ford 02 sensor and replace with the appropriate part number 5C-5Z-9F472-BA from Ford. It can also be found under the following interchange part numbers: SG1813, KN4-74, 15716 and 213-4630. Once you have your Escape oxygen sensor replaced, your EFI function will return to normal and your trouble code will be cleared.

Have any questions about this trouble code guide? Let me know below!

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