P0105

What it means

P0105 is the generic code for a fault in the manifold absolute pressure (MAP) or barometric pressure sensor circuit. The engine control unit has seen a signal from the sensor that is missing, out of range or does not make sense against other inputs such as throttle position, engine speed or the barometric reading at key-on. The exact test and thresholds vary by manufacturer and engine.

Symptoms

• Malfunction indicator lamp on
• Poor or hesitant acceleration
• Rough or unstable idle
• Hard starting or long cranking
• Black smoke or poor fuel economy
• Engine running in a reduced-power or limp mode

Possible causes

• Vacuum leak or split, loose or blocked vacuum hose to the MAP sensor (where fitted)likely
• Faulty MAP sensor giving a skewed or stuck signallikely
• Damaged wiring, poor connection or corroded terminals in the sensor supply, earth or signal circuitlikely
• Intake leak after the throttle body, such as a cracked intake hose, a loose clamp or a failed manifold gasketpossible
• Contamination or blockage at the sensor port, such as oil, soot or carbon depositspossible
• Fault in the sensor reference voltage supply caused by another shorted sensor on the same circuitpossible
• Engine control unit fault or a known outdated calibration (depends on make and model)rare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting engine speed, load and throttle position when the fault set. Check for other sensor or air system codes.
2. Inspect the MAP sensor, its connector and the wiring for damage, chafing, oil, water ingress and corrosion. Check any vacuum hose for cracks, kinks or blockage.
3. Check the intake system for leaks, including hoses, clamps, the throttle body seal and the manifold gasket.
4. With the ignition on and engine off, compare the live MAP reading with the expected barometric pressure for your altitude. It should be plausible and steady.
5. Watch the live MAP value as the engine idles and is then snapped open, and check it responds smoothly in line with throttle position and load.
6. Check the sensor supply voltage, earth and signal wire with a multimeter against the manufacturer's wiring diagram, looking for shorts, open circuits and voltage drop.
7. Check any other sensors that share the same reference supply, since a fault in one can pull down the voltage to all of them.
8. Where a replacement sensor is suspected, confirm the engine's mechanical condition and vacuum level first, as a mechanical fault can mimic a bad sensor. Procedure depends on model.

How to fix

• Repair or replace any leaking, split or blocked vacuum hoses, or intake leaks found.
• Repair damaged wiring or connectors, and clean or replace corroded terminals.
• Replace the MAP sensor if it reads out of range or fails the live data and voltage tests.
• Clean the sensor port carefully if it is contaminated, and find and fix the source of any oil or soot.
• Replace a faulty shorted sensor that is dragging down the shared reference supply.
• Apply any manufacturer-issued calibration update only if a known software fault applies to this vehicle.

Can I keep driving?

Nearby codes

• P0104GenericMass or Volume Air Flow Sensor A Circuit Intermittent
• P0106GenericManifold Absolute Pressure/Barometric Pressure Sensor Circuit Range/Performance