P1119
ChryslerManifold Absolute Temperature Circuit High Input
Medium SeverityThis code, P1119, indicates that your Chrysler's Engine Control Module (ECM) is receiving an abnormally high voltage signal from the Manifold Absolute Temperature (MAT) sensor circuit, which it interprets as a very low (cold) temperature. This electrical fault can lead to the ECM supplying too much fuel, impacting engine efficiency and potentially causing rough operation.
⚠️ Before You Begin (Safety First)
Always ensure the engine is cool before working near hot components. When dealing with electrical components, disconnect the negative battery terminal to prevent accidental shorts or shocks. Be mindful of rotating parts if the engine must be run for testing.
Common Symptoms
- Check Engine Light illuminated on the dashboard
- Engine runs rich, potentially causing black smoke from the exhaust
- Poor cold start performance or prolonged cranking
- Rough idle, especially when the engine is cold
- Reduced fuel economy
Common Causes
- Faulty Manifold Absolute Temperature (MAT) sensor itself, sending an incorrect high voltage signal
- An open circuit (break) in the MAT sensor's wiring, preventing a proper signal return
- A short to voltage in the MAT sensor circuit, where the signal wire is touching a higher voltage source
- Corroded or loose connections at the MAT sensor or ECM
- Less commonly, a faulty Engine Control Module (ECM)
Frequently reported on: Dodge Grand Caravan (2005-2010), Chrysler 300 (2006-2012), Jeep Wrangler (2007-2011), Dodge Ram 1500 (2004-2008)
Diagnostic Steps
- Begin by visually inspecting the Manifold Absolute Temperature (MAT) sensor and its connector for any obvious damage, corrosion, or loose wires. Ensure the harness is securely plugged in.
- With the engine off and cool, disconnect the MAT sensor. Using a multimeter, measure the resistance across the sensor's terminals. Compare this reading to your vehicle's service manual specifications for varying temperatures. An open circuit (infinite resistance) or significantly out-of-range reading indicates a faulty sensor.
- Next, check the wiring harness for continuity and shorts. With the sensor disconnected, probe the sensor's harness connector terminals with your multimeter to check for an open circuit back to the ECM. Also, check for any shorts to ground or shorts to power (battery voltage) on the signal wire.
- If the MAT sensor or its wiring is found to be faulty, replace the sensor. Be sure to use a direct OEM replacement or a high-quality aftermarket equivalent for proper fit and function.
- After replacement, clear the P1119 code using an OBD-II scanner and then test drive the vehicle to confirm the repair and ensure the code does not return.
👨🔧 When to Call a Professional
While replacing the sensor is a common DIY fix, if the issue persists after a new sensor is installed, it strongly suggests a more complex wiring or ECM fault. Tracing electrical circuits requires specialized tools and diagnostic knowledge; in such cases, it's best to consult a professional technician to avoid further damage.
Commonly Asked Questions
What does 'circuit high input' actually mean for the MAT sensor?
When the ECM detects a 'circuit high input' from the MAT sensor, it means the voltage signal it's receiving from that circuit is unusually high. This typically corresponds to the sensor reporting an extremely cold air temperature. If the actual intake air temperature isn't that cold, it indicates an electrical issue like an open circuit in the wiring or a faulty sensor sending a constantly high voltage.
Can I continue to drive my Chrysler with a P1119 code?
While you can likely drive the vehicle, it's not recommended for an extended period. The ECM will be receiving incorrect temperature data, causing it to run the engine overly rich (too much fuel). This can lead to increased fuel consumption, reduced engine performance, and potentially damage to emissions components like the catalytic converter over time. It's best to address it promptly.
How do I properly test the MAT sensor's electrical circuit?
To test the MAT sensor circuit, first, disconnect the sensor. You'll need a multimeter. With the ignition on (engine off), check for reference voltage (typically 5V) at one of the harness connector terminals. Then, check for a good ground connection at the other terminal. If those are present, you'll need to check the resistance of the sensor itself at various temperatures, as specified in your vehicle's service manual, to determine if the sensor is functioning correctly across its range. An open circuit or short in the wiring between the sensor and ECM would also cause this code.
Is the MAT sensor the same as the IAT sensor?
No, while they both measure air temperature, they often have different placements and sometimes separate functions. The Manifold Absolute Temperature (MAT) sensor is typically located in the intake manifold, measuring the temperature of the air *after* it has passed through the throttle body. The Intake Air Temperature (IAT) sensor is usually located within the air intake tract or air filter housing, measuring ambient air temperature entering the engine. Some vehicles integrate both functions into a single sensor, but P1119 specifically refers to the MAT circuit on Chrysler models.
What if I replace the MAT sensor and the P1119 code returns?
If replacing the MAT sensor doesn't resolve the P1119 code, your focus should shift to the wiring harness connecting the sensor to the ECM. You'll need to thoroughly inspect the wires for any breaks, chafing, or corrosion, paying close attention to areas where the harness might rub against other engine components. Also, carefully check the pins within the connector itself. If the wiring is intact and has proper continuity, then a faulty Engine Control Module (ECM) could be the culprit, though this is a much less common scenario.