Powertrain, generic (extended)

P227D Barometric Pressure Sensor C Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P227D is the high-voltage counterpart of P227C. On GM's 2018 diesel the sensor C input has a pull-up, so both a short to the supply and a broken signal wire push it above 90.2 % of 5 V (about 115.4 kPa); after 320 failures in 400 samples it is a Type B fault. The supercharged LT4 uses 90 % (115 kPa) and attributes the code only to a short to power, here as Type A with the MIL on the first trip, because its input reads an open line as low. GM's 2023-2024 twin-throttle engine flags a reading above 115 kPa held for 2 s over two trips. Since the atmosphere cannot produce such a value at the sensor positions concerned, the ECM switches to a substitute, and corrections for altitude or boost become less exact.

Likely causes

Signal wire of sensor C shorted to 5 V or battery voltage
Broken signal wire or sensor ground on inputs with pull-up
Sensor C internally defective

Symptoms

  • MIL on
  • Little change in driving; possibly reduced boost or poorer altitude compensation

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–400
Time0.5–2 h

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

Parts involved

barometric pressure sensorsensor wiring

Related codes

P227CP227AP227BP227EP2229P222D

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com.