What this code means
P0113 means the PCM may be seeing an intake air temperature sensor signal that is higher than expected, which often corresponds to an unrealistically cold temperature reading.
What the vehicle may do
- The vehicle may have a check engine light.
- The engine may run normally.
- Fuel control can be affected because the PCM may be using incorrect intake air temperature information.
Possible fault areas
- Possible MAF sensor/IAT sensor fault.
- Possible poor connection or loose terminal at the sensor connector area.
- Possible open in the TA circuit.
- Possible open in the SG2 circuit.
- Possible PCM-side issue after the sensor and wiring checks are proven good.
Diagnostic path
Open and frame the fault
For P0113 on this 2010 to 2015 Honda Civic with the 1.8 gas engine, I’m looking at an intake air temperature signal that may be reading like an extremely cold air temperature, or like a high sensor voltage. The vehicle may have a check engine light, may run normally, or can have fuel control affected because the PCM is working from bad intake air temperature information. Broadly, this can be a possible MAF sensor/IAT sensor issue, a connector or terminal problem, an open in the TA or SG2 circuit, or a PCM-side issue after the wiring checks good. Start with the basic system checks, then follow the electrical path in order. Don’t jump to a part until the data and circuit checks point there.
Confirm the failure is present
First, turn the ignition switch to ON (II), or press the engine start/stop button to select ON mode. With the HDS, look at IAT SENSOR in the data list. If the reading shows about －40 °F (－40 °C) or less, or 4.92 V or more, the failure is duplicated and you move into circuit isolation. If it does not show that, treat it as an intermittent at this time. The system is OK right now, so check for poor connections or loose terminals at the MAF sensor/IAT sensor area, and if captured operating data is recorded, try to reproduce the same conditions instead of guessing.
Use the jumper test to separate the sensor from the rest of the circuit
If the fault is present, turn the ignition switch to LOCK (0), or select OFF mode. Disconnect the MAF sensor/IAT sensor 5P connector. Install a jumper between terminal A and terminal B: terminal A is connector No. 4, RED/YEL, and terminal B is connector No. 5, GRN/YEL. Turn the ignition back to ON (II), or ON mode, and check IAT SENSOR in the HDS data list again. If it still indicates about －40 °F (－40 °C) or less, or 4.92 V or more, keep going into the wiring checks. If it no longer indicates that, the procedure calls for replacing the MAF sensor/IAT sensor.
Check the TA circuit voltage
Next, turn the ignition switch to LOCK (0), or select OFF mode, and remove the jumper wire. Turn the ignition back to ON (II), or ON mode. With the MAF sensor/IAT sensor 5P connector still disconnected, measure voltage on the TA circuit between connector No. 4, RED/YEL, and body ground. You’re looking for about 5.0 V. If about 5.0 V is present, the path moves to the SG2 open-wire check. If about 5.0 V is not present, the path moves to the TA open-wire check.
If TA voltage is present, check SG2 continuity
When the TA voltage check passes, turn the ignition switch to LOCK (0), or select OFF mode. Jump the SCS line with the HDS, disconnect PCM connector B, the 51P connector, and check continuity on the SG2 circuit. Check between PCM connector B No. 5, GRN/YEL, and MAF sensor/IAT sensor 5P connector No. 5, GRN/YEL. If continuity is missing, repair the open in the SG2 wire between PCM B5 and the MAF sensor/IAT sensor. If continuity is present, the SG2 wire is OK. At that point, update the PCM if it does not have the latest software, or substitute a known-good PCM. If P0113 goes away after the update, troubleshooting is complete. If P0113 goes away with the known-good PCM installed, replace the original PCM.
If TA voltage is missing, check TA continuity
When the TA voltage check does not show about 5.0 V, turn the ignition switch to LOCK (0), or select OFF mode. Jump the SCS line with the HDS, disconnect PCM connector B, the 51P connector, and check continuity on the TA circuit. Check between PCM connector B No. 30, RED/YEL, and MAF sensor/IAT sensor 5P connector No. 4, RED/YEL. If continuity is missing, repair the open in the TA wire between PCM B30 and the MAF sensor/IAT sensor. If continuity is present, the TA wire is OK. Then use the same PCM path: update the PCM if it does not have the latest software, or substitute a known-good PCM. If P0113 goes away after the update, troubleshooting is complete. If P0113 goes away with the known-good PCM installed, replace the original PCM.
Verify and close
Keep verification separate from the testing. After the identified repair, software update, or PCM substitution path, verify the repair and confirm P0113 stays gone. The key is to follow the split: prove the failure in data, use the jumper to separate the sensor from the circuit, check TA voltage, then check the correct open-wire path before making the final call. For more diagnostic training, visit stepdiagnostics.com.
Final check
Confirm the fault in scan data, isolate the sensor with the jumper test, then follow the TA and SG2 circuit checks in order before deciding on the repair.
For more guided automotive diagnostics, visit STEP Diagnostics.
