Parts
$20–80
P0108 — MAP Sensor Circuit High Voltage
CAUTIONIs it safe to drive? Driveable, but the MAP fault makes the engine run RICH under load, which fouls spark plugs and can overheat or clog the catalytic converter over time — get it checked within a week.
What P0108 means
The MAP sensor signal is reading above 4.9V continuously, which the ECU interprets as maximum boost pressure even at idle. The ECU may enrich fuel delivery to compensate or go into a limp mode.
Most likely causes (in order)
- Short to voltage on the signal wire (most common wiring fault)
- MAP sensor failed high internally
- Open ground circuit at the MAP sensor
- Damaged wiring harness — signal wire contacting a 5V or 12V source
- Faulty ECU (rare — rule out sensor and wiring first)
Symptoms you might notice
- Hard starting
- Poor fuel economy
- Engine runs rich
- Black smoke or fuel smell from exhaust
- Check engine light
What to check first
With the key on and engine off, check the MAP sensor reference voltage (should be ~5V) and ground (should be 0V) at the connector. If those are correct and the signal wire still reads high with the sensor unplugged, the fault is in the harness — a wire is shorting to voltage somewhere between the sensor and ECU.
Repair cost & difficulty
Labor
0.3–0.7 hr
Difficulty
DIY-friendly