The OBDII trouble code of P1122 is something that can be a huge problem for your Honda. This check engine code refers to the throttle position sensor, which is basically a potentiometer that informs your ECU of how much your throttle blade is open. Your ECU then uses this value to determine how best to operate your engine by controlling spark and fuel events.
When you have this specific code, which pretty much means that the throttle position sensor is reporting a value that’s too high for your ECU, or higher than what your ECU expects. This DTC code can cause huge problems for your Honda Accord, especially if it’s an automatic transmission. Because your ECU does not have the proper throttle reference, you should not drive your vehicle or attempt to drive your car with this check engine light on.
Today I’ll be showing you how to resolve this OBDII check engine code, and how to test a Honda Accord TPS sensor. Because this SOHC Honda Prelude is using a F23A engine, we’ll be showing you how to take care of your P1122 trouble code.
What causes the P1122?
When you depress your gas pedal, the throttle cable attached to it will slowly open your throttle body. When the throttle cable is opening your throttle butterfly, the throttle position sensor (TPS) recognizes the movement and reports it to the ECU.
There can be a few causes for the P1122 trouble code, and this trouble code can often be accompanied by other codes that refer to throttle position, or lean conditions for your Honda Accord.
- Bad throttle body
- Poor battery
- Bad ECU
Unfortunately, the F23A throttle body does not feature a throttle position sensor that can be serviced. If you learn how to test a Honda Accord TPS, and you find your TPS to be bad you will sadly need a whole new throttle body.
Your F23A TPS is connected by way of a three pin weatherproof connector. Make sure not to confuse your Manifold Absolute pressure (MAP) sensor with your TPS, as the connectors are very similar. Note the orientation of the MAP sensor (on top of your F23 intake manifold / throttle body) and your TPS sensor (side of your throttle body – opposite the throttle butterfly / cable )
Clearing the trouble code from your Honda instrument cluster can be easy, but if you don’t want the P1122 code to return, you will have to learn how to test a Honda Accord TPS.
To begin testing the wiring connector to your TPS to make sure it’s working correctly, unplug your TPS connector. To reach your TPS connector, you may have to disconnect your intake pipe as well as your MAP connector and PCV hoses.
It’s not easy accessing the throttle position sensor or the wiring, but once you have the plug free you are ready to learn how to test a Honda Accord TPS. Take your multimeter and connect the black lead to the negative terminal of your battery, and turn the key to the “ON” position.
Not sure how to use a multimeter? Check our DIY How To Article here.
We’ll be using the diagram above to test your Honda Accord TPS, and fix the issue that has led to your OBDII trouble code of P1122. We’ll be testing for power and ground first at this three pin connector. With your multimeter connected to the battery ground, gently probe the front of your Honda Accord TPS at PIN C for a switched power source.
This wire powers the potentiometer inside your throttle position sensor, make sure you have switched power here. If not, make sure your key is turned to the “ON” position.
Next check PIN A for the low reference or ground signal to the TPS. This ground must be present for your TPS to operate correctly. If you have both power and ground at these terminals, it’s time to test the signal wire of your Honda Accord TPS.
PIN B is the signal wire or the TPS signal wire for your Honda Accord. Reconnect your throttle position sensor, and with the key turned to the “ON” position, you will be backpinning PIN B. Doing this will allow you to connect the TPS and test the output of the signal wire, or PIN B in this scenario.
Not sure how to backpin this connector? Use a straightened paper clip and insert into the PIN B terminal, with the paper clip exiting to the wire side. Now you can have your friend get into the car, and with the key set to the “ON” position slowly press on your accelerator.
Using your multimeter, you should see voltage at this middle pin. At a fully closed state, your Honda Accord TPS should report a voltage signal of around .5-1.0 volt of signal. At wide open throttle (WOT) with the throttle fully opened, you should see close to 5 volts of signal at this middle pin.
If you are working solo, you can use your hand to slowly depress the throttle open simply by using your other hand. If you have the reported voltage above at the middle pin or PIN B of your Honda Accord TPS sensor, then the next test to perform is the voltage range of your signal wire.
With the middle pin backprobed still, slowly open your throttle position sensor while watching your voltage. You should have a uniform and even scaling of the voltage to match how slowly and evenly you are opening the throttle.
Make sure to check for any gaps or skips in voltage, or any odd irregularities that could cause your P1122 trouble code. Test while you are slowly opening your throttle blade, as well as slowly closing your throttle blade. If these tests work out, your P1122 trouble code may lie elsewhere in your vehicle. If you have learned how to test a Honda Accord TPS and find that your TPS is bad or failed, replace it to resolve your OBDII DTC code.
Have any questions about our How To Test a Honda Accord TPS DIY guide? Leave them for us below!