What this code means
P0113 may indicate the PCM is seeing a high-voltage condition on the intake air temperature sensor circuit.
What the vehicle may do
- The vehicle may use substitute air-temperature information.
- The engine can sometimes show starting, idle, or fuel-control changes.
- The malfunction indicator may be on even if drivability feels mostly normal.
Possible fault areas
- Possible intake air temperature sensor signal concern
- Possible connector or terminal concern at the MAF sensor/IAT sensor connector
- Possible wiring open in the signal or sensor ground side
- Possible PCM input concern
Diagnostic path
Code overview
On this Civic, P0113 is an intake air temperature sensor circuit high-voltage code. In plain terms, the PCM is seeing an IAT signal that may be higher than expected. The vehicle may run with substitute air-temperature logic, and depending on conditions it can affect starting, idle quality, or fuel control. The broad fault areas are possible sensor signal issues, connector or terminal problems, wiring opens in the IAT signal or sensor ground side, and less often a PCM input concern. Start with the basic system checks, then follow the circuit path instead of guessing at parts.
Duplicate the fault
First, turn the vehicle to the ON mode. On the HDS, look at IAT Sensor (1) Voltage. If that value is more than 4.92 V, the failure is duplicated. That confirms the code-setting condition is present right now, so the rest of the diagnosis can stay focused on why the PCM is seeing a high IAT voltage.
Check sensor circuit response with a jumper
There is no direct method in this path to test the component by itself, so the diagnosis works through the related circuit response. Turn the vehicle off as needed, disconnect the MAF sensor/IAT sensor 4P connector, then jump terminals No. 2 and No. 4 with a jumper wire. Turn the vehicle back to the ON mode and confirm IAT Sensor (1) Voltage on the HDS. Normal here is less than 4.92 V. If the voltage drops into the normal range, the path points to a problem with the MAF sensor/IAT sensor. If it does not, keep going into the related circuit checks.
Check the TA and SG1 circuits for opens
Before disconnecting the PCM connector, jump the SCS line with the HDS and wait more than 1 minute. Then disconnect the MAF sensor/IAT sensor 4P connector and disconnect PCM connector E (80P). With IG Mode OFF, perform the TA open-wire inspection. Normal is less than 1 Ω. Then perform the SG1 open-wire inspection the same way, with IG Mode OFF. Normal there is also less than 1 Ω. If either check is abnormal, the problem is in the circuit. Use the correct terminal identification before probing; do not guess at connector locations.
PCM conclusion and takeaway
If the sensor response check and the TA and SG1 open-wire inspections all indicate normal, the remaining conclusion in this diagnostic path is a PCM problem. The key is to duplicate the high-voltage reading first, then separate sensor response from open-circuit faults before calling the PCM. For more diagnostic training, visit stepdiagnostics.com.
Final check
P0113 is often best approached as an electrical signal diagnosis: confirm the high reading, check circuit response, then test the related wiring before making a PCM call.
For more guided automotive diagnostics, visit STEP Diagnostics.
