What Does P012C Mean?
The ECM has detected that the turbocharger/supercharger inlet pressure sensor circuit downstream of the throttle valve is producing a voltage below the minimum expected threshold. This low signal typically indicates a short to ground in the signal wire, a failed sensor with an internally grounded output, or loss of the 5V reference voltage supply to the sensor.
Common Causes
35%
Failed inlet pressure sensor with internally shorted output circuit pulling signal voltage to ground
25%
Signal wire shorted to ground from heat damage, chafing near turbo components, or melted insulation
20%
Loss of 5V reference voltage to the sensor due to another sensor on the shared bus shorting the reference to ground
20%
Water intrusion or corrosion in the sensor connector causing signal to be shunted to ground through moisture bridging
Diagnostic Steps
1
Check the inlet pressure sensor voltage on a scan tool. A reading near 0V or 0 kPa confirms a low circuit condition. Disconnect the sensor connector; if voltage at the ECM rises, the sensor is internally shorted.
2
Verify 5V reference voltage at the sensor connector with the sensor disconnected. If the reference is missing or below 4.5V, systematically disconnect other sensors on the same reference bus to locate the short.
3
Inspect the sensor wiring harness for heat damage from turbo components. The high temperatures near the turbocharger can melt wire insulation and cause shorts to nearby ground paths.
4
Check the sensor connector for water intrusion, especially on sensors mounted in exposed locations. Dry the connector and apply dielectric grease to prevent recurrence.
5
Measure resistance from the signal wire to ground at the ECM connector with the sensor disconnected. A low resistance reading (below 10K ohms) indicates a short to ground in the harness.
Estimated Repair Cost
$100 - $450
Parts + labor, varies by vehicle and location
The ECM has detected that the turbocharger/supercharger inlet pressure sensor circuit downstream of the throttle valve is producing a voltage below the minimum expected threshold. This low signal typically indicates a short to ground in the signal wire, a failed sensor with an internally grounded ou...
The most common cause of P012C (Turbocharger/Supercharger Inlet Pressure Sensor Circuit Low (Downstream of throttle valve)) is: Failed inlet pressure sensor with internally shorted output circuit pulling signal voltage to ground
Typical repair costs for P012C range from $100 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A stuck-low pressure reading causes the ECM to believe the intake is under high vacuum. This can result in incorrect fueling, potential over-boost conditions, and the vehicle may enter reduced power mode to protect the engine.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P012C to identify the root cause.
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Quick Info
Category
Powertrain
System
Turbocharger/Supercharger Boost Control System
Difficulty
Type
Generic (SAE)
Recommended Tools
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