What does it mean?
P1108 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: BARO Pressure Sensor Circuit High Input .
Symptoms
- Check engine light on with a barometric reading well above real atmospheric pressure
- Rich mixture, black smoke and a strong exhaust smell
- Rough idle, hesitation and reduced power
- Higher fuel consumption than normal
- Hard starting, particularly when the engine is warm
- Emissions test failure and, in some cases, plug fouling over time
Likely causes
- Open or high-resistance sensor ground, letting the signal float toward reference voltage
- Signal wire shorted to the 5 V reference or to battery voltage in a damaged loom
- Corroded connector terminals bridging the signal and reference pins
- Faulty sensor with an internal fault that holds the output high
- Water ingress into the sensor body or connector after washing or heavy rain
- Poor module ground raising the reference level of several circuits
- Module input circuit fault, checked only when everything else is proven
How to fix it
- Read the live barometric value and compare it with the true atmospheric pressure; an inflated value confirms the high input
- Unplug the sensor and check the signal pin with the ignition on — reference voltage only should be present
- Voltage-drop test the sensor ground; excessive drop is the most frequent cause of a high reading
- Inspect the connector for corrosion, moisture and terminals that have partly melted together
- Follow the loom for chafe points where the signal wire could touch a live circuit
- Clean and reseal the connector, or repair the ground wire, then re-check the value
- Replace the sensor if the reading stays high with a proven ground and reference