P1112
FordIntake Air Temperature (IAT) Sensor Circuit Intermittent Low Voltage
Medium SeverityThis code indicates that the Intake Air Temperature (IAT) sensor is sending an intermittently low voltage signal to the Powertrain Control Module (PCM), suggesting a potential fault in the sensor or its circuit. This can lead to incorrect fuel mixture calculations, impacting engine performance and fuel economy.
⚠️ Before You Begin (Safety First)
Always ensure the vehicle is turned off and the battery is disconnected before performing any electrical work or component replacement to prevent electrical shock or damage. Allow the engine to cool down before working near hot components.
Common Symptoms
- Check Engine Light illuminated
- Decreased fuel economy
- Rough idle
- Hesitation or poor acceleration
- Black smoke from exhaust (in some cases, due to rich mixture)
- Difficulty starting (especially in extreme temperatures)
Common Causes
- Faulty Intake Air Temperature (IAT) sensor
- Corroded or loose electrical connections at the IAT sensor or PCM
- Damaged or frayed wiring in the IAT sensor circuit
- Short circuit to ground in the IAT sensor circuit
- Contamination of the IAT sensor element
- Rarely, a faulty Powertrain Control Module (PCM)
Frequently reported on: Ford F-150 (2000-2008), Ford Explorer (1998-2005), Ford Ranger (1999-2007), Ford Focus (2000-2007)
Diagnostic Steps
- Locate the Intake Air Temperature (IAT) sensor. On many Ford vehicles, it's integrated into the Mass Air Flow (MAF) sensor or located in the intake manifold/air ducting.
- Inspect the electrical connector and wiring leading to the IAT sensor for any signs of corrosion, damage, or loosenness. Clean any visible corrosion with electrical contact cleaner.
- Disconnect the IAT sensor connector.
- Using a multimeter, test the resistance of the IAT sensor at various temperatures if possible (refer to a service manual for expected values). Also, check for continuity and voltage at the harness connector.
- If the sensor tests faulty or if the wiring is damaged, replace the IAT sensor or repair the wiring harness as needed.
- Clear the P1112 code using an OBD-II scanner and test drive the vehicle to confirm the repair.
👨🔧 When to Call a Professional
If the check engine light persists after replacing the IAT sensor and inspecting the wiring, or if the vehicle exhibits severe performance issues, it's best to consult a professional mechanic for further diagnosis, as there might be a more complex underlying electrical issue or PCM fault.
Commonly Asked Questions
What does P1112 mean?
P1112 indicates that the Intake Air Temperature (IAT) sensor circuit is intermittently sending a low voltage signal to the engine's computer, often on Ford vehicles.
Can I drive with a P1112 code?
While you can usually drive with this code, it's recommended to address it promptly as it can lead to reduced fuel economy and poorer engine performance over time.
Where is the IAT sensor located on a Ford?
On many Ford vehicles, the IAT sensor is either a standalone sensor in the intake air ducting or integrated directly into the Mass Air Flow (MAF) sensor.
How much does it cost to fix a P1112 code?
Replacing a faulty IAT sensor is generally inexpensive, often costing between $20-$100 for the part, plus minimal labor if you do it yourself.
Do I need to replace the MAF sensor if the IAT is integrated?
Yes, if the IAT sensor is integrated into the MAF sensor and it's confirmed faulty, you would need to replace the entire MAF sensor assembly.