Code
P227E
Generic
P — Powertrain
Barometric Pressure Sensor C Circuit Intermittent/Erratic
Views:
UK: 15
EN: 31
RU: 23
AI status
Completed
Completed
100%
Causes
- Damaged, chafed or pinched wiring for BARO sensor circuit C
- Corroded, loose or contaminated connector pins at the sensor or harness
- Intermittent short to battery or ground
- Faulty BARO sensor (internal intermittent)
- Poor sensor reference voltage or ground at PCM
- Water intrusion or contamination in the sensor/connector
Symptoms
- Malfunction Indicator Lamp (MIL) on (intermittent)
- Intermittent rough idle, hesitation or stumbling
- Occasional hard starting or stalling
- Variable fuel trim corrections and inconsistent fuel economy
- Possible reduced engine power or limp-home behaviour if ECU limits operation
What to check
- Read freeze-frame and extended data to see conditions when the code set (engine speed, temperature, altitude, MAP/BARO values).
- Visually inspect BARO sensor and harness for damage, corrosion, water entry or pinched wiring.
- Backprobe the sensor connector and monitor signal while key ON / engine OFF and while running; watch for voltage dropouts or spikes.
- Confirm 5V reference (or manufacturer-specified reference) and good ground at the sensor connector.
- Compare BARO (key ON) value to ambient atmospheric pressure (local barometric value) and to MAP sensor reading at key-on — BARO should equal MAP at KOEO.
- Wiggle/connectivity test: flex wiring and connectors while watching live data for intermittent changes.
Signal parameters
- Reference supply: typically 5.0 V (verify with vehicle data); should be stable within manufacturer tolerance.
- Signal output: commonly about 0.5–4.5 V (varies by design); equals ambient pressure at key ON, KOEO MAP ≈ BARO.
- Typical ambient pressure: ~101 kPa (sea level); expect BARO readout near local barometric pressure ± small tolerance.
- No rapid spikes or dropouts; signal should change smoothly with altitude or forced vacuum/pressure tests.
Diagnostic algorithm
- Retrieve trouble code(s), freeze-frame and live sensor data. Note when the fault occurs (cold/hot, vibration, throttle state).
- Visually inspect sensor, connector and harness for damage, corrosion, moisture, or poor repairs. Repair obvious issues.
- With connector connected, backprobe sensor: verify stable reference voltage and ground continuity. Repair any poor reference/ground first.
- With key ON engine OFF, compare BARO reading to local barometric pressure (online weather or handheld barometer). They should match closely.
- Start engine and monitor BARO vs MAP: BARO (KOEO) should equal MAP; during operation BARO should remain stable and not fluctuate rapidly. If the signal drops out or fluctuates during wiggle test, repair wiring/connector.
- If electricals are good but signal still intermittent, replace the BARO sensor with a known good unit and retest.
- If replacement sensor and wiring checks do not clear the issue, inspect PCM connector pins for damage and consider PCM diagnosis or reflash as last resort.
- After repairs, clear codes and test-drive under conditions that previously reproduced the fault to confirm resolution.
Likely causes
- Wiring harness worn at a chassis/flexible point causing intermittent break when moving
- Loose terminal or push-back pin in connector causing intermittent contact
- Sensor internal electronics failing when hot/cold
- Connector corrosion from road contamination or previous fluid intrusion
- Aftermarket device or repair that disturbed the wiring
Fault status
Status
Barometric Pressure Sensor C circuit intermittent or erratic — the sensor signal is fluctuating or dropping intermittently. Inspect wiring, connector, sensor and reference/ground; verify BARO and MAP readings.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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