Powertrain, generic (extended)

P227C Barometric Pressure Sensor C Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P227C flags a voltage from pressure sensor C that is too low. GM's 2018 tables show two variants. On the diesel, where sensor C measures turbocharger inlet pressure and the input has a pull-up, only a short to ground pulls it below 39.4 % of 5 V (about 50.2 kPa); 320 failures in 400 samples make it a Type B fault. On the supercharged 6.2 L LT4 the limit is 40 % (50.9 kPa), and both a grounded and an open line count, as Type A with the MIL on the first trip. GM's 2023-2024 twin-throttle engine looks at the pressure value: below 50 kPa for 2 s, two trips. GM bulletin 22-NA-188 (1.3 L L3T and 2.0 L LSY turbo) links P227C after an ECM replacement to a redesigned MAF sensor that requires the matching calibration. P227D is the high counterpart.

Likely causes

Signal wire of sensor C shorted to ground
Open signal or 5 V supply line on inputs that read an open circuit as low
Replacement control module without the calibration that matches the fitted sensor
Sensor C internally defective

Symptoms

  • MIL on, on some engines immediately
  • Engine runs on a substitute value, at most slightly less power

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

P227DP227AP227BP227EP2228P222C

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov.