What this code means
P0113 may mean the PCM is seeing an intake air temperature sensor circuit signal that is outside the expected range.
What the vehicle may do
- The MIL may illuminate.
- The vehicle may have drivability symptoms, or it may appear to run normally depending on the fault.
Possible fault areas
- Possible IAT signal circuit fault.
- Possible sensor ground circuit fault.
- Possible connector or terminal concern.
- Possible IAT sensor response issue.
- Possible PCM-side circuit concern after wiring and sensor checks.
Diagnostic path
Opening context
On this Ram 1500 Classic with the 5.7 HEMI, P0113 points us toward the Intake Air Temperature Sensor 1 circuit. In plain terms, the PCM may be seeing an intake air temperature signal that does not make sense for the operating conditions. The MIL may be on, and depending on the fault, the truck may have drivability complaints or it may seem to run normally. The broad areas to keep in mind are the IAT signal circuit, the sensor ground circuit, connector condition, sensor response, and, only after the circuit is proven out, the PCM side of the circuit. For this diagnostic, the monitor runs continuously with the ignition on, and it also uses battery voltage greater than 10.4 volts as a monitor gate. The code sets when the PCM detects the IAT Sensor input voltage below 0.3 - 0.43 volts depending on calibration for 2.3 seconds.
Start with pre-checks and confirm the code
Start with the basic pre-diagnostic checks before you get into circuit testing. Then start the engine and let it reach normal operating temperature. While the engine is running, stay clear of the fan, belts, and pulleys, and keep loose clothing away from moving parts. With the scan tool, read the codes and record them on the repair order. What matters here is whether P0113 is active or pending. If it is active or pending, continue with the pinpoint tests. If it is not active or pending, treat it as an intermittent condition and work that path instead of forcing a hard-fault diagnosis.
Check the IAT signal circuit for voltage
Next, check the K21 IAT signal circuit for a short to voltage. Turn the ignition off, disconnect the PCM C2 harness connectors, then turn the ignition back on. Measure voltage on the K21 IAT signal circuit at the IAT sensor harness connector. If any voltage is present, repair the K21 IAT signal circuit for a short to voltage, then verify the repair and confirm the code stays gone. If there is no voltage present, move on to the signal circuit resistance check.
Check the IAT signal circuit for open or high resistance
With the ignition off, measure resistance on the K21 IAT signal circuit between the IAT sensor harness connector and the PCM C2 harness connector. The decision point is whether resistance is below 3.0 Ohms. If it is below 3.0 Ohms, continue to the sensor ground circuit test. If it is not below 3.0 Ohms, repair the K21 IAT signal circuit for an open circuit or high resistance, then verify the repair and confirm the code stays gone.
Check the sensor ground circuit
Now check the K915 sensor ground circuit for an open or high resistance condition. Measure resistance between the IAT sensor harness connector and the PCM C2 harness connector. Again, the decision point is below 3.0 Ohms. If the ground circuit is below 3.0 Ohms, continue to the PCM signal-read test. If it is not below 3.0 Ohms, repair the K915 sensor ground circuit for an open circuit or high resistance, then verify the repair and confirm the code stays gone.
Simulate the sensor signal
At this point, the test checks whether the PCM can read the IAT signal correctly when the circuit is pulled low. Turn the ignition off and disconnect the IAT sensor harness connector. Install a jumper wire between the K21 IAT signal circuit and the K915 sensor ground circuit in the IAT sensor harness connector. Turn the ignition on and read the IAT sensor signal voltage on the scan tool. With the jumper in place, the voltage should be below 0.1 volt. If it is below 0.1 volt, replace the Intake Air Temperature Sensor, then verify the repair and confirm the code stays gone. If it is not below 0.1 volt, continue to the wiring, connector, and PCM side of the diagnosis.
Inspect wiring, connectors, and PCM side
For the final circuit check, use the wiring diagram as your guide and inspect the wiring and connectors between the Intake Air Temperature Sensor and the PCM. Look for chafed, pierced, pinched, or partially broken wires. Also check for broken, bent, pushed-out, or corroded terminals. While monitoring scan tool data for this circuit, wiggle test the wiring and connectors and watch for the data to change or for the DTC to reset. Perform any service bulletins that apply. If you find a problem, repair it as necessary, then verify the repair and confirm the code stays gone. If no problems are found after those checks, replace and program the PCM, then verify the repair and confirm the code stays gone.
Closing takeaway
The key with P0113 is to prove the circuit before condemning a part: confirm the code, check the IAT signal for unwanted voltage, verify signal and ground circuit resistance, simulate the sensor input, then inspect the harness and connector behavior under a wiggle test before making the PCM call. For more diagnostic training, visit stepdiagnostics.com.
Final check
P0113 is often diagnosed by proving the signal and ground circuits first, then using sensor simulation and connector inspection before considering module-related causes.
For more guided automotive diagnostics, visit STEP Diagnostics.
