P1119
FordManifold Absolute Temperature Circuit High Input. This indicates the Powertrain Control Module (PCM) has detected a voltage signal from the Manifold Absolute Temperature sensor circuit that is consistently above a specified maximum threshold.
Medium SeverityWhen you get a P1119 code, it means the engine computer is seeing a voltage signal from the Manifold Absolute Temperature (MAT) sensor that's too high, suggesting the sensor might be reading incorrectly or has an open circuit. This can lead to the engine's fuel mixture being off, affecting performance and fuel economy.
⚠️ Before You Begin (Safety First)
Always allow the engine to cool down before working on any under-hood components. Be cautious around hot engine parts and electrical connections. Disconnect the negative battery terminal before inspecting electrical components to prevent accidental short circuits or electrical shock.
Common Symptoms
- Check Engine Light illuminated
- Rough idle or poor engine performance
- Reduced fuel economy
- Engine may run rich or lean
- Hesitation or stumbling during acceleration
Common Causes
- Faulty Manifold Absolute Temperature (MAT) sensor
- Open circuit or high resistance in the MAT sensor signal wire
- Corrosion or damage in the MAT sensor connector
- Damaged or chafed wiring leading to the MAT sensor
- Faulty Powertrain Control Module (PCM), though this is rare
- Poor ground connection for the MAT sensor circuit
Frequently reported on: Ford F-150 (2004-2008), Ford Escape (2001-2007), Ford Focus (2000-2004), Ford Ranger (1998-2011)
Diagnostic Steps
- First, let's locate the Manifold Absolute Temperature (MAT) sensor. It's usually found in the intake manifold or the air intake tube, past the air filter but before the throttle body. Its job is to tell the computer how hot the air entering the engine is.
- Visually inspect the MAT sensor and its electrical connector. Look for any obvious signs of damage, corrosion, or wires that might be cut, frayed, or disconnected. Remember, a 'high input' often means there's an open in the circuit, preventing a proper signal.
- Disconnect the electrical connector from the MAT sensor. Check the pins inside the connector for corrosion or bending. Clean any corrosion using electrical contact cleaner. Ensure a good, snug fit when reconnecting.
- With a multimeter, you can test the MAT sensor's resistance. At room temperature, it should have a specific resistance value (check your vehicle's service manual for exact specs). If it reads open or very high resistance, it's likely faulty. You can also monitor the voltage at the sensor's signal wire with the key on engine off, expecting a reference voltage from the PCM.
- If the sensor appears good and the wiring looks fine, clear the P1119 code using an OBD-II scanner. Then, start the engine and drive the vehicle to see if the code returns. Sometimes, a loose connection can cause an intermittent issue.
- If the code returns, consider replacing the MAT sensor. This is usually a straightforward task, often involving just unplugging the old sensor and screwing in a new one. Always use a quality replacement part to ensure accurate readings for your engine.
👨🔧 When to Call a Professional
If after checking the wiring and replacing the sensor the code persists, or if you are unsure about testing electrical circuits, it's best to consult a professional technician. They have specialized diagnostic tools to pinpoint more complex electrical issues or PCM faults.
Commonly Asked Questions
What does a 'High Input' mean for the MAT sensor?
In simple terms, 'High Input' often means the computer is seeing a higher than expected voltage signal from the sensor. For a temperature sensor, this usually indicates the sensor is perceiving an extremely cold temperature, or more commonly, there's an open circuit in the wiring or the sensor itself is faulty and not sending a proper signal.
Can I drive with a P1119 code?
While you can typically drive with this code, it's not recommended for long. The engine's computer will use a default value for intake air temperature, which can cause incorrect fuel-air mixture, leading to reduced fuel economy, poorer performance, and potentially higher emissions. It's best to address it promptly.
Is the MAT sensor the same as the IAT sensor?
That's a good question! While they both measure air temperature, the MAT (Manifold Absolute Temperature) sensor is often found in older systems or integrated into the MAF sensor, measuring air temperature specifically in the intake manifold. The IAT (Intake Air Temperature) sensor measures the temperature of the air entering the engine, often located in the air intake tube. Functionally, they do similar things by providing temperature data to the PCM, but their specific placement and naming can vary by vehicle.
How can I test the MAT sensor with a multimeter?
To test it, you'll need to disconnect the sensor and measure its resistance across its terminals. The resistance should change significantly with temperature. You can use an ice bath or hot water (carefully!) to see if the resistance changes as expected. Always refer to your vehicle's service manual for the exact resistance specifications at various temperatures.
What if replacing the sensor doesn't fix P1119?
If a new sensor doesn't solve it, the problem is most likely in the wiring or the electrical connector itself. This means you'll need to meticulously check for opens, shorts, or high resistance in the wires connecting the MAT sensor to the PCM. A damaged PCM is possible but much less common.