What Does P012B Mean?
The ECM has determined that the turbocharger/supercharger inlet pressure sensor downstream of the throttle valve is producing readings that are outside the expected range or do not correlate with other engine parameters such as throttle position, RPM, and MAP sensor values. The sensor may be electrically functional but providing inaccurate or implausible pressure data during certain operating conditions.
Common Causes
35%
Inlet pressure sensor drifting out of calibration, providing readings that do not match actual manifold conditions
25%
Partially blocked or kinked vacuum hose to sensor causing delayed or attenuated pressure response
20%
Vacuum leak in the intake system between the throttle valve and the sensor tap point skewing the pressure reading
20%
Moisture or oil contamination in the sensor vacuum port degrading diaphragm response and accuracy
Diagnostic Steps
1
Compare the turbo inlet pressure sensor reading with the MAP sensor reading on a scan tool at various RPM and load conditions. Both should track similarly when measuring the same pressure area.
2
Inspect the vacuum hose to the sensor for kinks, partial blockage, or oil/moisture contamination. Blow through the hose to verify it is clear and replace if restricted.
3
Perform a smoke test on the intake manifold to check for vacuum leaks between the throttle body and the sensor measurement point that could skew readings.
4
With engine off and key on, apply known vacuum levels to the sensor using a hand vacuum pump and compare the scan tool reading to the applied value. The sensor should track accurately within 1-2 kPa.
5
Check for intake system modifications or aftermarket parts that may have altered the pressure dynamics in the area where the sensor measures.
Estimated Repair Cost
$100 - $450
Parts + labor, varies by vehicle and location
The ECM has determined that the turbocharger/supercharger inlet pressure sensor downstream of the throttle valve is producing readings that are outside the expected range or do not correlate with other engine parameters such as throttle position, RPM, and MAP sensor values. The sensor may be electri...
The most common cause of P012B (Turbocharger/Supercharger Inlet Pressure Sensor Circuit Range/Performance (Downstream of throttle valve)) is: Inlet pressure sensor drifting out of calibration, providing readings that do not match actual manifold conditions
Typical repair costs for P012B range from $100 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Inaccurate inlet pressure data causes improper boost control calculations, potentially leading to over-boost or under-boost conditions. Over-boost can cause severe engine damage from detonation, while under-boost reduces available power during acceleration.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P012B 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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