The Civic TPS sensor in your Honda is basically a potentiometer sensor that reads the position of your throttle blade. As you depress the gas pedal in your 1.7 liter Honda Civic, the cable pulls open the throttle body. When your throttle body opens air will rush into the engine, and the Honda Civic TPS sensor tells your Powertrain Control Module how much the throttle body is open.
Your Honda computer uses this information to operate the engine efficiently. When your Honda Civic TPS Sensor begins to go bad you can have a lot of different problems with your 1.7 liter VTEC engine. Today I’ll be showing you how to test a Civic TPS Sensor in a 2002 Honda sedan EX with a SOHC engine in it.
The throttle position sensor is mounted to the other side of your Civic throttle body, and is connected by way of a three pin weatherproof connector. There’s 3 wires from this wiring connector, and they represent power, ground and the signal wire for your Civic TPS Sensor.
Symptoms of a bad Civic TPS Sensor
One of the early warning signs that your throttle position sensor is going bad is sluggish throttle response. If your engine is not responding to your throttle inputs or the engine speed or RPM is rising on it’s own, the TPS sensor could be going bad.
Some of the other problems from a failing TPS sensor can also be an OBDII trouble code. This will cause your MIL status to light on your 2002 Honda Civic instrument cluster. When you see the familiar check engine light on your dash, a bad Civic TPS sensor can cause these error codes.
- P0122: Throttle Position Sensor Circuit Low Input.
- P0123: Throttle Position Sensor Circuit High Input.
There can be other instances when the sensor is sending or transmitting too high or too low of a signal. These trouble codes can also arise when you have a OBDII P0122 or P0123 trouble code.
- P1121: Throttle Position Sensor Signal Lower Than Expected.
- P1122: Throttle Position Sensor Signal Higher Than Expected.
Testing your Honda Civic TPS Sensor for Power
Your throttle position sensor has 3 pins to it, and you will be using an automotive multimeter to test the unit. If you aren’t sure what a multimeter is, or how to read DC voltage, check our guide here. The first pin you will be testing is the power wire, which is PIN A as shown in the diagram below.
Unplug your Civic TPS sensor and measure PIN A for power using your multimeter. The wire coming out of PIN A should be a YELLOW wire with a BLUE stripe. Make sure you have your Civic ignition turned to the “ON” position. If you have 5 volts of DC power at this wire, move onto PIN C which is the ground wire.
The wire coming out of PIN C is a GREEN wire with a YELLOW stripe in it. There should be a low reference ground signal at this wire. If you have both power and ground at PIN A and C respectively, the next thing you must do it measure the signal coming out of your Civic TPS Sensor.
Measuring your Civic TPS Sensor Signal
The last wire you will be checking in our How To DIY article for your Civic TPS Sensor is PIN B. This is the middle wire which should have a RED wire with a BLACK stripe in it. This wire represents the signal wire that your throttle position sensor emits to your ECU. Make sure your key is still turned to the “ON” position.
Reconnect your TPS sensor and you will be using one of two methods to measure the signal wire. You can either use a paper clip that’s unbent and inserted into the BACK of PIN B, or pierce the RED / BLACK wire.
With your key at the “ON” position, you must measure the voltage at this signal wire. With the throttle plate closed you should see around .8-1.1 volts of DC signal here. Now using your other hand you can manually open your throttle body 100% open. The Civic TPS Sensor signal wire should read anywhere between 4.7-4.9 volts of DC power at wide open throttle.
The measurements at your throttle position sensor may vary slightly, however your sensor should read around these voltage values. If the sensor is not responding within this range, it’s time to replace your TPS and calibrate the sensor so that you restore proper operation.
Of course if you have a B series Honda engine swap in your Civic, you can use any number of our aftermarket TPS sensors as a replacement. We carry Blackworks B series TPS sensors as well as the BLOX Racing TPS.
Have any questions about our How To Guide to testing your Civic TPS Sensor? Leave us a message below and let us know!
