P1112
ToyotaIntake Air Temperature (IAT) Sensor Circuit Intermittent Low Voltage
Medium SeverityThis code indicates that the Intake Air Temperature (IAT) sensor is sending a signal that is intermittently too low, suggesting a problem with its circuit or the sensor itself. Drivers may notice issues with fuel efficiency or engine performance as the engine control unit struggles to adjust fuel delivery based on incorrect air temperature readings.
⚠️ Before You Begin (Safety First)
Always ensure the vehicle is turned off and cool before working on any engine components. Disconnect the battery's negative terminal to prevent electrical shorts or accidental component activation. Allow hot engine components to cool down to avoid burns.
Common Symptoms
- Check Engine Light illumination
- Decreased fuel economy
- Poor engine performance
- Rough idle
- Increased emissions
- Hesitation during acceleration
Common Causes
- Faulty Intake Air Temperature (IAT) sensor
- Damaged or corroded wiring in the IAT sensor circuit
- Loose or corroded electrical connections at the IAT sensor or PCM
- Melted or shorted IAT sensor wiring
- Contamination or debris on the IAT sensor element
- Faulty Powertrain Control Module (PCM) (less common)
Frequently reported on: Toyota Camry (2002-2006), Toyota Corolla (2003-2008), Toyota RAV4 (2001-2005), Toyota Tacoma (2000-2004), Toyota Sienna (2004-2007)
Diagnostic Steps
- Locate the Intake Air Temperature (IAT) sensor, typically found in the intake manifold, air intake tube, or mass airflow sensor housing.
- Visually inspect the IAT sensor and its wiring for any obvious signs of damage, corrosion, or frayed insulation.
- Gently disconnect the electrical connector from the IAT sensor.
- Inspect the connector terminals for corrosion, bending, or looseness. Clean them if necessary using electrical contact cleaner.
- If accessible and the sensor is dirty, carefully clean the sensor element with appropriate sensor cleaner, avoiding harsh chemicals.
- Reconnect the electrical connector securely to the IAT sensor.
- Clear the P1112 code using an OBD-II scanner and test drive the vehicle to see if the code returns.
- If the code persists, consider replacing the IAT sensor with a new one.
👨🔧 When to Call a Professional
If, after inspecting and cleaning the IAT sensor and its connections, the code persists or if you notice significant drivability issues like rough idling or stalling, it's time to consult a professional mechanic for advanced diagnostics.
Commonly Asked Questions
What is the Intake Air Temperature (IAT) sensor?
The IAT sensor measures the temperature of the air entering the engine, providing this data to the engine control unit (ECU) to adjust fuel delivery and ignition timing for optimal performance.
Can I drive with a P1112 code?
While often not immediately critical, driving with a P1112 code can lead to reduced fuel economy, poor engine performance, and increased emissions. It's best to address it promptly.
Where is the IAT sensor located on my Toyota?
The IAT sensor can be located in various places depending on the Toyota model and engine, including the air intake duct, the intake manifold, or integrated within the mass airflow (MAF) sensor. Consult your vehicle's service manual for the exact location.
Do I need special tools to replace the IAT sensor?
Generally, no. Most IAT sensors can be replaced with basic hand tools like a screwdriver or a small wrench, along with electrical contact cleaner for cleaning connections.
How do I know if the IAT sensor is truly faulty?
After checking wiring and connections, you can test the sensor's resistance using a multimeter at different temperatures, comparing the readings to your vehicle's specifications. However, simply replacing an inexpensive sensor is often the quickest fix if other checks don't reveal issues.