What does it mean?
P1143 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Pressure Sensor Circuit range/Performance Problem (low input) .
Symptoms
- Malfunction indicator lamp on with reduced power under load
- Hesitation, flat spots or a lack of pull during acceleration
- Rough idle or an unstable idle speed
- Higher fuel consumption and occasional black or grey smoke
- The vehicle entering limp mode under heavier throttle
Likely causes
- Blocked or restricted pressure port, hose or passage feeding the sensor
- Cracked, split or disconnected hose so the sensor never sees real pressure
- Signal circuit shorted to ground or to the sensor ground wire
- Open or high resistance in the 5 V reference supply to the sensor
- Sensor element drifted low or damaged by overpressure or contamination
- Corroded connector terminals adding resistance in the signal path
- Genuine low pressure in the system being monitored, so the sensor is reporting correctly
How to fix it
- Compare the sensor reading at key on, engine off with atmospheric pressure or the known static value for that system
- Verify the actual pressure with a mechanical gauge before assuming the sensor is at fault
- Inspect the pressure hose or port for cracks, blockage, oil sludge and loose fittings
- Measure the 5 V reference, signal and ground at the sensor connector with the key on
- Substitute a known pressure at the sensor if the system allows, and watch the live value follow it
- Check the signal wire for a short to ground with the sensor unplugged
- Replace the sensor only after the plumbing, wiring and real pressure have all been verified