P1109
ChryslerP1109 Chrysler - Intake Air Temperature (IAT) Sensor B Intermittent. This code indicates that the Powertrain Control Module (PCM) has detected an intermittent circuit or rationality issue with the Intake Air Temperature (IAT) Sensor B.
Medium SeverityThis code signifies an intermittent electrical problem with the Intake Air Temperature Sensor circuit, meaning the signal from the sensor is fluctuating or dropping out periodically. This can lead to incorrect fuel mixture calculations by the engine's computer, potentially impacting engine performance and fuel efficiency.
⚠️ Before You Begin (Safety First)
Always allow the engine to cool down before working on any engine components. Disconnect the negative battery terminal before performing any electrical repairs to prevent accidental shorts or damage to the vehicle's electrical system. Wear appropriate personal protective equipment, such as gloves and eye protection.
Common Symptoms
- Check Engine Light illuminated
- Poor engine performance
- Reduced fuel economy
- Engine running rough or idling poorly
- Hard starting in extreme temperatures
Common Causes
- Faulty Intake Air Temperature Sensor B (intermittent operation)
- Corroded or loose electrical connectors at the IAT sensor or PCM
- Damaged wiring in the IAT sensor circuit
- PCM software glitch (less common)
- Short to voltage or ground in the IAT sensor circuit
Frequently reported on: 2000-2005 Dodge Ram 1500, 2001-2006 Chrysler Sebring, 2000-2004 Jeep Grand Cherokee, 1999-2004 Dodge Dakota, 2000-2006 Dodge Stratus
Diagnostic Steps
- Locate the Intake Air Temperature Sensor B. Its location can vary; consult your vehicle's service manual. It's often found in the intake manifold or air intake tube.
- Visually inspect the sensor and its electrical connector for any signs of damage, corrosion, or loose connections.
- Disconnect the battery's negative terminal.
- Carefully disconnect the electrical connector from the IAT sensor. Inspect the pins for bends or corrosion.
- If corrosion is present, clean the terminals using electrical contact cleaner and a small brush.
- Reconnect the electrical connector, ensuring it's secure.
- Reconnect the negative battery terminal.
- Clear the P1109 code using an OBD-II scanner.
- Start the engine and drive the vehicle to see if the code returns or if symptoms persist.
- If the code returns, consider replacing the IAT Sensor B. This usually involves twisting or unbolting the old sensor and installing a new one.
👨🔧 When to Call a Professional
If after inspecting and potentially replacing the sensor, the code persists or if you experience significant performance issues, it's time to consult a professional mechanic or automotive electrician. Intermittent electrical issues can be complex to diagnose without specialized tools.
Commonly Asked Questions
What does P1109 mean for my Chrysler vehicle?
P1109 indicates an intermittent issue with the Intake Air Temperature (IAT) Sensor B circuit, meaning the engine's computer is receiving inconsistent readings about the temperature of the air entering the engine.
Can I drive my car with a P1109 code?
While you can likely drive the car, it's advisable to address the issue promptly. An intermittent IAT sensor can lead to decreased fuel efficiency, poor engine performance, and potentially increased emissions.
Is IAT Sensor B the same as IAT Sensor A?
Not necessarily. Some vehicles, especially those with more complex intake systems or superchargers/turbochargers, might have multiple IAT sensors. Sensor B would refer to a specific one, often post-turbo/supercharger or in a different manifold location.
How do I test the IAT sensor?
You can test an IAT sensor using a multimeter to check its resistance at different temperatures, comparing the readings to specifications found in your vehicle's service manual. Alternatively, an advanced scan tool can read its live data values.
What if replacing the IAT sensor doesn't fix P1109?
If replacing the sensor doesn't resolve the code, the problem likely lies in the wiring harness or electrical connector leading to the sensor, or less commonly, an internal issue with the PCM. A thorough circuit diagnosis by a professional would be the next step.