P1119
BMWManifold Absolute Temperature Circuit High Input
Medium SeverityWhen your BMW sets a P1119 code, it means the engine computer, or DME, is seeing a voltage signal from the Manifold Absolute Temperature (MAT) sensor that's too high. This high voltage tells the DME the incoming air is colder than it actually is, leading to incorrect fuel mixture adjustments and potential drivability issues.
⚠️ Before You Begin (Safety First)
Before working on any vehicle, always ensure the engine is off and cool to the touch. Disconnect the negative battery terminal to prevent accidental shorts or injury from electrical components. Be mindful of hot engine parts and sharp edges.
Common Symptoms
- Check Engine Light illuminated on the dashboard.
- Engine might run rough, especially during cold starts.
- Noticeable decrease in fuel economy.
- Hesitation or lack of power under acceleration.
- Increased emissions (might fail an emissions test).
Common Causes
- A faulty Manifold Absolute Temperature (MAT) sensor itself, which is unable to provide an accurate voltage signal.
- An open circuit or a short to voltage in the MAT sensor's wiring harness, leading the DME to interpret a high voltage.
- Poor electrical connections at the MAT sensor or the DME.
- Less commonly, an internal fault within the DME (engine computer) itself.
Frequently reported on: 2001-2006 BMW 3 Series (E46), 2004-2010 BMW 5 Series (E60), 2000-2006 BMW X5 (E53), 2007-2013 BMW 3 Series (E90)
Diagnostic Steps
- First, locate the Manifold Absolute Temperature sensor. It's usually found in the intake manifold or the intake piping after the air filter.
- Visually inspect the MAT sensor and its electrical connector for any obvious damage, corrosion, or loose connections. Make sure the wiring insulation isn't chafed or broken.
- With the ignition off, disconnect the MAT sensor's electrical connector. Using a multimeter, you'll want to check for proper voltage reference (typically 5V) and ground at the connector terminals when the ignition is on. This tells you if the DME is providing power to the sensor.
- You can also test the MAT sensor's resistance with a multimeter while it's removed and at different temperatures. As the temperature increases, the resistance should decrease. Consult your vehicle's repair manual for specific resistance values at different temperatures.
- If the sensor tests bad, or the wiring is intact and power is present, replacing the MAT sensor is the next step. It's usually held in by a clip or threaded in.
- After replacement, clear the fault code using an OBD-II scanner and test drive the vehicle to confirm the repair.
👨🔧 When to Call a Professional
If you've checked the sensor and wiring and the issue persists, or if you're uncomfortable with electrical diagnostics, it's always best to consult a qualified BMW technician. They have specialized diagnostic tools and expertise to pinpoint complex electrical faults or internal DME issues.
Commonly Asked Questions
What does a 'High Input' actually mean for the MAT circuit?
In diagnostic terms, 'High Input' typically means the voltage signal being sent to the DME from the sensor is higher than its normal operating range. For a MAT sensor, a high voltage usually corresponds to a very low (or 'cold') temperature reading, or it could indicate an open circuit in the sensor or wiring.
Can I drive my BMW with a P1119 code?
While you might be able to drive the car, it's not recommended for extended periods. The DME is operating with incorrect air temperature data, which can lead to rich or lean running conditions, increased fuel consumption, higher emissions, and potentially long-term engine damage if left unaddressed.
Is replacing the MAT sensor a difficult job for someone new to DIY repairs?
For most BMW models, replacing the Manifold Absolute Temperature sensor is a fairly straightforward job. The difficulty is usually rated as 'Medium' because it involves working with electrical connectors and sometimes requires a bit of patience to access the sensor. With the right tools and a good repair guide, it's a great learning opportunity.
Will this code cause my car to fail an emissions test?
Yes, it absolutely can. Because the P1119 code indicates the engine's air temperature readings are off, the fuel mixture will likely be incorrect. This leads to higher than normal emissions of pollutants, which would cause your vehicle to fail most emissions inspections.