P222C

Code

Generic P — Powertrain

Barometric Pressure Sensor B Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 25 EN: 41 RU: 29

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Page language: EN

Causes

Damaged or shorted signal wire to ground
Corroded or loose connector/pins at the sensor
Failed Barometric Pressure Sensor (Sensor B)
Missing or low sensor supply voltage (5V or 3.3V reference)
Open or high-resistance ground
Water intrusion or contamination in connector

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Reduced engine performance or limp mode in some vehicles
Poor idle quality or stalling
Incorrect boost control (turbo vehicles) or turbo over/under-boost
Reduced fuel economy and drivability issues
Inaccurate altitude/compensation-related behavior

What to check

Retrieve freeze-frame and live data for BARO sensor B and compare to expected ambient pressure and MAP/MASS readings
Perform visual inspection of the BARO sensor connector, wiring harness and nearby components for damage, corrosion or moisture
Backprobe sensor connector and measure signal voltage with key ON (engine OFF) and with engine running
Verify sensor supply/reference voltage (typically 5V or 3.3V) and ground continuity at the connector
Wiggle test wiring while monitoring live data to find intermittent faults
Disconnect the sensor and observe code behavior (note: some vehicles will set additional codes when sensor unplugged)

Signal parameters

Typical sensor output: approx. 0.5–4.5 V (varies by application) — low fault often when signal < ~0.1–0.5 V
Sensor supply/reference: typically 5.0 V or 3.3 V from ECM (verify with OEM data)
Expected ambient pressure reading: ~95–105 kPa at sea level (value varies by altitude)
Response: output should change gradually with ambient pressure; it should not be a steady near-zero voltage
Resistance/continuity: signal wire should show continuity to ECM pin with ignition off (no short to ground)

Diagnostic algorithm

Read and record scan tool data: freeze frame, stored codes, BARO sensor B live value and compare to BARO sensor A / MAP if available.
Do a visual inspection of the sensor, connector and wiring harness for damage, corrosion, oil or water intrusion. Repair visible damage.
With key ON (engine OFF), backprobe the sensor connector:
Measure reference supply voltage (expect ~5.0 V or ~3.3 V depending on vehicle).
Measure sensor signal voltage (should be within typical operating range; near-zero indicates low circuit).
Measure ground continuity between sensor ground pin and chassis ground/ECM ground.
If reference voltage is missing or low, trace supply back to ECM and check for short to ground or poor connection. Repair as needed.
If supply and ground are OK but signal is low, inspect signal wire for short to ground. Disconnect connectors along the circuit and check for continuity to ground where not expected.
If wiring checks good, swap the BARO Sensor B with a known-good sensor (or replace) and re-test. If code clears and readings normalize, replace the sensor.
If replacement sensor does not fix the code, perform continuity and resistance checks between the sensor connector and the ECM pin to rule out harness faults. Repair or replace harness as necessary.
If harness and sensor are good and fault persists, test or reflash ECM if supported by OEM procedures — only after verifying wiring and sensor integrity.
After repairs, clear codes and perform road test and live-data verification at different altitudes/engine loads to confirm the fix.