P1119
VWManifold Absolute Temperature Circuit High Input
Medium SeverityThis code, P1119, means your engine computer, the ECM, is seeing an unexpectedly high voltage signal from the Manifold Absolute Temperature (MAT) sensor circuit. This usually indicates an electrical problem, like an open circuit or a short to voltage, leading the ECM to believe the intake air is much colder than it actually is, which can affect fuel delivery and engine performance.
⚠️ Before You Begin (Safety First)
Before you start any work, always make sure the engine is off and cool. Disconnect the negative battery terminal to prevent accidental shorts or electrical shocks. Wear appropriate safety glasses and gloves. Be careful when working around hot engine components or moving parts.
Common Symptoms
- Check Engine Light illumination
- Poor fuel economy
- Black smoke from the exhaust
- Rough idle or stalling, especially when cold
- Reduced engine power or hesitation
- Engine running rich
Common Causes
- Faulty Manifold Absolute Temperature (MAT) sensor
- Open circuit or short to voltage in the MAT sensor wiring harness
- Corroded or damaged MAT sensor electrical connector
- Faulty Engine Control Module (ECM) (rare, but possible)
Frequently reported on: Volkswagen Jetta (2006-2014), Volkswagen Golf (2005-2013), Volkswagen Passat (2007-2015), Volkswagen Beetle (2006-2010)
Diagnostic Steps
- First, you want to visually inspect the Manifold Absolute Temperature (MAT) sensor and its wiring harness. Look for any obvious signs of damage, like frayed wires, melted insulation, or corrosion on the connector. Sometimes, it's as simple as a broken wire you can see.
- With the ignition off, carefully disconnect the electrical connector from the MAT sensor. Check the terminals inside the connector for bent pins, corrosion, or looseness. A bad connection can cause a high resistance, mimicking an open circuit.
- Using a multimeter, you'll need to test the sensor's resistance. The resistance should change with temperature. If it reads infinite resistance, that indicates an open circuit within the sensor itself. Consult your vehicle's service manual for specific resistance values at different temperatures.
- Next, we need to check the circuit wiring. With the connector still disconnected from the sensor, turn the ignition to the 'ON' position (engine off). Use your multimeter to check for reference voltage (usually 5V) and a good ground signal at the connector terminals. A 'high input' code could mean the signal wire is shorted to this reference voltage or an open ground.
- If the sensor tests bad or the wiring checks out, the most common fix is to replace the Manifold Absolute Temperature (MAT) sensor. Ensure you get the correct part for your specific VW model. Carefully install the new sensor and reconnect the electrical connector securely.
- After replacement, clear the P1119 code using an OBD-II scan tool. Then, start the engine and let it run for a few minutes to see if the code returns. Take it for a test drive to confirm the repair.
👨🔧 When to Call a Professional
If you're unsure about any diagnostic steps or if the issue persists after replacing the sensor, it's always best to consult with a qualified mechanic. They have specialized diagnostic tools to check the wiring harness for continuity or shorts, which can be tricky to do correctly without experience. Don't guess with electrical problems; get professional help if you're stuck.
Commonly Asked Questions
What exactly does 'Manifold Absolute Temperature Circuit High Input' mean?
It means the signal coming from your Manifold Absolute Temperature (MAT) sensor, which tells the ECM how warm the air entering the engine is, is sending a voltage that is too high. This usually suggests an open circuit or a short to voltage somewhere in the sensor or its wiring, making the ECM think the air is extremely cold.
Will my car still be drivable with a P1119 code?
Yes, your car will likely still be drivable, but you might notice some issues. The ECM will often default to a 'safe' fuel strategy when it sees this error, which usually means running rich (adding too much fuel). This can lead to poor fuel economy, rough running, and possibly a loss of power.
Where is the MAT sensor usually located on a VW engine?
The Manifold Absolute Temperature (MAT) sensor is typically located in the intake manifold or sometimes integrated into the Manifold Absolute Pressure (MAP) sensor. You'll need to consult your specific vehicle's service manual or do a quick online search for your year, make, and model to pinpoint its exact location.
Can I ignore this code, or is it important to fix?
It's important not to ignore this code. While it might not seem critical right away, consistently running rich due to incorrect temperature readings can lead to other, more expensive problems down the road, such as damaging your catalytic converter or building up excessive carbon deposits in the engine.
What tools will I need to replace the MAT sensor?
Typically, you'll need basic hand tools like a socket set, a screwdriver, and potentially a Torx bit set depending on your vehicle. A multimeter is also essential for proper diagnosis of the sensor and wiring, and an OBD-II scan tool will be needed to clear the code after the repair.