What it means
The module detects an electrical fault in the turbocharger or supercharger inlet pressure sensor A circuit, downstream of the throttle valve.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Sensor A measures pressure in the turbocharger or supercharger inlet passage after the throttle valve. The control module checks the sensor circuit for an electrical fault, such as an open or short, rather than judging whether the pressure reading matches engine conditions. It sets P012A when that circuit check fails.
Common causes
Most likely first.
- Pressure sensor A failed
- Sensor wiring open, shorted, or damaged
- Loose or corroded connector
- Related reference voltage or ground fault
Symptoms
- Check engine light on
How to diagnose it
- Record freeze-frame data and any related codes to see when the module detected the sensor A circuit fault.
- Locate sensor A in the inlet passage downstream of the throttle valve and check its connector for looseness, corrosion, or damaged pins.
- Inspect the sensor A wiring along its route for breaks, chafing, or contact with hot or moving parts.
- With the vehicle wiring diagram, check the sensor A reference supply, ground, and signal circuit for opens or shorts.
- If the wiring and supplies meet the manufacturer's specification, test sensor A and replace it only if it fails.
Common fixes
- Reconnect and secure the sensor A connector.
- Repair damaged or chafed sensor A wiring.
- Clean or repair corroded connector terminals.
- Repair a reference voltage or ground fault affecting sensor A.
- Replace sensor A if circuit tests confirm it has failed.
Can I keep driving?
With only the check-engine light reported, normal driving may be possible, but avoid heavy acceleration or boost until the fault is diagnosed. The module may have less reliable pressure information for engine control.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.