DTC P0123 – How To Service Your TPS Sensor

The OBDII Trouble Code P0123 is for a high voltage signal being sent to your vehicle’s ECU/PCM by your Throttle Position Sensor ( TPS ) from either a short or a faulty sensor, in which your ECU/PCM will not have correct reference to the position of your throttle plate and consequently will not know how to run the motor naturally.

As your ECU is dependent on the data that your TPS provides, you will need to service this before attempting to drive your vehicle. Often times many customers come to us about this problem after they have installed a new throttle body or perhaps serviced the Throttle Position Sensor but did not install it correctly.

We’ll be taking a look at this trouble code in a 1998 Honda CRV, and showing you how to fix your ODBII error code by testing your Throttle Position Sensor. As Honda does not normally sell this sensor seperately, we will provide you instead with the OE interchange part number of 911-753, Throttle Position Sensor.

This sensor is connected by a 3 prong weather proof connector and is located on top of your throttle blade assembly, you may want to unwind your throttle cables to allow for free movement when you are testing your TPS.

You will need a voltmeter to test the sensor itself for an open condition, and then we will be testing directly at the ECU to see if the wire between the PCM and the sensor is the problem.

Step 1: Start the engine and hold the engine speed at 3000 RPM without load ( in neutral  or Park if you are working on an automatic ) until the motor has come to operating temperature. You will know you are ready when the radiator fans kick on, at which point you will turn off the car but leave your ignition switch to the “ON” position.

Step 2: Using your datalogger or scan tool, reference the throttle position that is being reported to your ECU. Your operating range for this value should be 10% and under at idle, and 90% and above for full throttle open. If the value for this is within the operating range, you must test your sensor itself next.

To test your Throttle Position sensor ( TPS ) in your CR-V, unplug the three pin connector and measure the voltage between the pin 1 and pin 3 terminals using an voltmeter while the key is set to the “ON” positon but the motor is off. If you do not have 5 volts here, it’s time to replace your throttle position sensor yourself and install it using the proper volt ranges.

If you do have 5 volts powering this sensor, there is another issue in the vehicle that is causing the issue. Next we’ll be testing at the ECU to determine if the ECU itself is powering the sensor.

Disconnect the ECU plugs D (16 pin ) on your OBDII ECU and check for voltage between pin 10 and 11, there should be 5 volts at these 2 pins sending power to your TPS. If you read voltage coming out of the ECU, then the wire between your TPS and your ECU pin 11 must be replaced as there is a short or intermittent problem that is causing your OBDII code.

Lastly we’ll be checking the voltage at your ECU plug C, a 31 pin connector on your OBDII ECU and checking for voltage between the 18 pin and the 28 pin.

If there is voltage at these 2 pins, you will need to replace the wire from the C18 pin to the TPS itself as there is a short or intermittent problem that is causing your OBDII code.

You have now completed the repair of your DTC OBDII trouble code P0123, congratulations!