P012D

What it means

P012D means the engine control unit has seen a signal voltage from turbocharger or supercharger inlet pressure sensor 'A' that is higher than the expected range. This sensor measures air pressure at the compressor inlet, usually between the air filter and the turbo. The fault sets when the voltage stays too high, which points to a short to voltage, an open circuit or ground fault, or a faulty sensor. Sensor position and exact thresholds vary by model and engine.

Symptoms

• Engine warning light on
• Reduced power or limp mode
• Poor or inconsistent boost response
• Turbo underboost or overboost faults stored alongside
• Rough running or hesitation under load
• Possible increase in smoke or fuel consumption

Possible causes

• Faulty turbo inlet pressure sensorlikely
• Damaged, chafed or corroded wiring to the sensor, such as a short to the supply voltage or an open signal or ground wirelikely
• Poor connection at the sensor plug, with bent, loose or corroded terminals or water ingresslikely
• Open circuit in the sensor ground wire, which pulls the signal highpossible
• Fault in the 5 V reference supply shared with other sensors, giving a high readingpossible
• Blocked or restricted air intake or filter, or oil contamination in the sensor port affecting the readingrare
• Fault inside the engine control unit or outdated software, where a known fault exists for that modelrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data. Note whether other sensor circuit codes sharing the same 5 V reference are present.
2. Check for technical service information or known issues for the specific model and engine.
3. Inspect the sensor, its plug and the wiring for damage, chafing, heat damage, oil contamination, water and corrosion. Check the terminals for tightness.
4. With the ignition on and engine off, view live data for the inlet pressure sensor. It should read close to atmospheric pressure. A reading stuck at maximum suggests a circuit high fault.
5. Unplug the sensor and check the 5 V reference and ground at the plug against the manufacturer's wiring diagram. Check for voltage on the signal wire where specified.
6. Test the signal, reference and ground wires for continuity and for shorts to voltage or to each other, with the battery and control unit connectors disconnected where required.
7. Check that the air intake and air filter are clear, and that the sensor port is free of blockage or oil.
8. If wiring and sensor test fine, check for control unit software updates and test the control unit as the manufacturer directs.

How to fix

• Replace the inlet pressure sensor if it is faulty or reads incorrectly against known values.
• Repair or replace damaged wiring and fix any short to voltage or open circuit found.
• Clean, repair or replace corroded or loose connector terminals, and fit a new connector if the plug is damaged.
• Restore the ground or reference supply if either is faulty, including any sensor sharing that supply.
• Clear any blockage or oil contamination from the sensor and air intake path, and renew a blocked filter.
• Update the control unit software only where a known fault for that model is documented, or repair or replace the control unit if proven faulty.

Can I keep driving?

Nearby codes

• P012CGenericTurbocharger/Supercharger Inlet Pressure Sensor A Circuit Low
• P012EGenericTurbocharger/Supercharger Inlet Pressure Sensor A Circuit Intermittent/Erratic