P0105Powertrain
Powertrain · SAE
MAP Sensor Circuit Malfunction
Meaning
No valid signal or a completely irrational signal from the manifold absolute pressure (MAP) sensor. Without a reliable MAP measurement the ECU cannot correctly calculate airflow or ignition timing.
Common causes
- MAP sensor failure (no output)
- Disconnected or cracked vacuum reference hose (analogue MAP sensors)
- Open circuit or short in wiring
- Connector damage
- 5 V reference voltage fault at ECU
Symptoms
- MIL illuminated
- Rough idle
- Fuel trim errors (rich or lean)
- Poor throttle response
- Engine may not start or run poorly
Severity
High severity: without MAP information the ECU cannot correctly calculate airflow or ignition timing.
What to do
- Check vacuum hose connection and integrity (analogue MAP)
- Measure MAP sensor output voltage at idle
- Verify 5 V reference and ground at the connector
- Compare MAP reading to ambient pressure (should match near atmospheric at key-on engine-off)
- Replace sensor if reference voltage and ground are good