Powertrain, generic · Fuel and air metering

P012B Turbocharger/Supercharger Inlet Pressure Sensor A Circuit Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

The turbocharger/supercharger inlet pressure sensor A sits between the air filter and the compressor. The engine uses it for the compressor pressure ratio, to judge air filter restriction (ambient minus inlet pressure) and to cross-check the other pressure sensors. P012B is a plausibility fault: the signal is electrically valid but stuck or offset. On GM's supercharged 6.2 V8 the sensor must read 50–115 kPa and agree within 10 kPa with MAP and ambient pressure after the engine has been off for more than 8 s; while running, it is compared with modelled values (fault above about 25–30 kPa). GM normally needs two trips, one in some 2019 applications. In operation inlet pressure is slightly below ambient because of filter losses, so a clogged filter or blocked intake lowers it further.

Likely causes

Sensor oiled (crankcase vent often joins before the compressor) or drifted
Air filter heavily clogged or intake blocked or collapsed
Leak in the intake pipe between filter and compressor or at the sensor flange
High resistance in the wiring
Comparison sensor (MAP, baro, MAF) wrong or software

Symptoms

  • Check engine light on
  • Loss of power or boost limitation
  • Possibly no noticeable symptoms

Repair estimate

DifficultyEasyDIY possible
Parts and labour€20–250
Time0.3–1.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

turbocharger inlet pressure sensor aair filterintake ductsensor wiring

Related codes

P012AP012CP012DP006DP006CP0106

References: law.cornell.edu, gsi.ext.gm.com, gsi.ext.gm.com, patents.google.com.