How To Test a Ford Taurus Oxygen Sensor

How To Test a Ford Taurus Oxygen Sensor


Typically when your Taurus oxygen sensor goes bad or fouls out, it’s not always obvious to the owner. Ford Taurus problems from a failed 02 sensor can be subtle at first but over time the issues can become more exaggerated. Of course the most obvious signs of trouble is a check engine light. Using a scan tool enables you to read the stored DTC trouble code in your Ford engine computer.

Because your 3.0 liter V6 engine has more than one upstream oxygen sensor, there can be several stored OBDII codes. The upstream Taurus oxygen sensor is the one that delivers the current air/fuel ratio of the exhaust to your Ford computer. Your Ford computer then uses this data to properly adjust the amount of fuel being sprayed into your engine.

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There’s a few different names for the upstream 02 sensor. It’s also called Sensor 1, or the front oxygen sensor. These are installed into the header or the collector of your exhaust header, and before the catalytic converter. Today I’ll be showing you how to test your Taurus oxygen sensor in a 2004 Ford with a 3.0 liter V6 engine in it.

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Some of the more common OBDII trouble codes are :
P0131 Upstream Heated Oxygen Sensor Circuit Out Of Range Low Voltage.
P0132 Upstream Heated Oxygen Sensor Circuit High Voltage.
P0133 Upstream Heated Oxygen Sensor Circuit Slow Response.

These OBDII Diagnostic Trouble Codes signify that there’s an issue with your upstream O2 sensor, or Sensor 1.

There’s several symptoms that are still detectable, while not obvious. Some of the more common Ford Taurus problems are shown below.

Symptoms of a bad Taurus oxygen sensor

  • Bad gas mileage
  • Harsh shifting transmission
  • Engine hesistation
  • Black soot from tailpipe
  • Check Engine Light ON

Bank 1 vs Bank 2 Taurus oxygen sensor – What’s the difference?

Depending on the issue your Ford Taurus is having, your failed 02 sensor may be identified as O2S11 or O2S12. Bank 1 is the side of your engine that cylinder 1 resides on, and Bank 2 is the other side. In our 2004 Ford Taurus, the side with cylinder 1 or Bank 1 is facing towards the firewall. Today we are dealing with the Bank 2 O2 sensor, which is facing towards the front of the Ford.

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If your OBDII trouble code dictates that your Ford Taurus Bank 1 O2 sensor has failed, you’ll need to remove the intake manifold to test it.

Testing your Taurus oxygen sensor for Power

Before you can start our guide, you’ll need to use a digital multimeter to check for your oxygen sensor heater function. Because we’ll be starting with Bank 2, all you need to do is reach down and unclip the O2 sensor. Once this sensor is disconnected, you need to turn the Ford Taurus ignition to the “ON” position.

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The first wire you’ll be checking is PIN A on the OBDII engine harness. Remember that you are testing the ENGINE side of your Taurus O2 sensor. Because these are female metal connectors, you have to be careful to not force or shove the multimeter lead into the connector.

With your key turned to the “ON” position, this wire should have 12 volts of power. This is just one part of your oxygen sensor heater, and the other wire is PIN B. If you have 12 volts at PIN A, check PIN B which should also have 12 volts of power at this wire. The last wire to check is PIN C which is a ground wire.

To check for a ground signal at the Taurus oxygen sensor, switch the positive and negative leads of your multimeter around. You need to check PIN C for ground and make sure that you don’t force the leads down the connector. If these three wires check out, chances are that your oxygen sensor is bad depending on what your OBDII trouble code is.

Testing your Taurus oxygen sensor Signal

The last wire is PIN D which is what you need to measure the signal, but to do this you will need to reconnect your upstream O2 sensor. Once it’s connected, follow the wire that leads to PIN D back to a safe spot in your engine bay.

Because the car needs to be started, you’ll need to find a place where you can test safely. Make sure to keep clear of the engine and especially the cooling fans. If your Ford Taurus is reporting a P0131 trouble code, it means your Ford O2 sensor sees a low voltage. The specific wording for this code is Upstream Heated Oxygen Sensor Circuit Out Of Range Low Voltage

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If your Ford Taurus is running too lean, or not enough fuel this P0131 trouble code will be triggered. This happens when your oxygen sensor reports a voltage lower than what the engine is expecting.

Your upstream Taurus oxygen sensor can read as low as 0.050 to 0.100 volts.

If your trouble code is P0132 for too high of a voltage signal, this means that your Taurus engine is running rich. The specific verbiage behind the P0132 trouble code is Upstream Heated Oxygen Sensor Circuit High Voltage.

It’s basically the reverse of the too lean condition, where the engine computer is receiving a signal that’s more than what it expects. This happens because of the excessive fuel present in your exhaust stream. This means the engine is spraying more fuel into the engine for some reason this will increase your upstream or front oxygen sensor voltage.

Left untreated this will cause your exhaust gas temperatures to rise to the point your catalytic converter burns out. This is caused by the excessive hydrocarbons present in the exhaust stream.

Because the front Taurus oxygen sensor normally cycles in a closed loop environment, this means your voltage will fluctuate. It should cycle from .1 to .9 volts of DC power, meaning that your engine and sensor has warmed up properly.

If your Ford Taurus has a P0131 trouble code, this signal will be stuck below .5 volts and will not cycle. If the Ford engine computer is showing a P0132 the upstream Taurus oxygen sensor will be stuck over .9 voltage.

You can correct the Ford Taurus problems related to your Taurus oxygen sensor by installing a replacement O2 sensor. Tested your upstream Ford O2 sensor in your 3.0 liter Duratec engine and it’s not responding as you want? Install a replacement unit now and make sure to use a scan tool to clear your OBDII trouble code.

Have any questions about our Taurus oxygen sensor DIY Guide? Leave them for us below and let us know!