P227C: Barometric Pressure Sensor C Circuit Low

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.

Symptoms

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

Most 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

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the connector and the pressure port
2. With the connector unplugged, check whether the signal wire is making contact with ground.
3. With the engine off, compare the reading with the atmospheric pressure from the barometric sensor
4. Watch how it changes when starting and accelerating
5. Clean it with a suitable product, or replace it if it does not respond

Good to know

• Repair difficulty: medium
• It affects emissions.

What each character of P227C means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 2: Fuel injection
• 7C: Specific fault in that system

Frequently asked questions

Can I keep driving with code P227C?

You can drive with caution to a repair shop. Avoid demanding power if the car is in limp mode.

What causes code P227C?

The most common causes are: 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.

Related codes

• P227DBarometric Pressure Sensor C Circuit High
• P227ABarometric Pressure Sensor C Circuit
• P227BBarometric Pressure Sensor C Circuit Range/Performance
• P227EBarometric Pressure Sensor C Circuit Intermittent/Erratic
• P2228Barometric Pressure Sensor A Circuit Low
• P222CBarometric Pressure Sensor B Circuit Low

Sources

• gsi.ext.gm.com: 18OBDG04 Engine Diagnostics
• gsi.ext.gm.com: 18OBDG03A Engine Diagnostics
• gsi.ext.gm.com: 24OBDG07
• static.nhtsa.gov: MC 10225718 0001

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.