Code
P2228
Generic
P — Powertrain
Barometric Pressure Sensor A Circuit Low
AI status
Completed
Completed
100%
Causes
- Faulty barometric pressure (BARO) sensor
- Open or short to ground in sensor signal wire
- Poor or corroded connector/pins
- Loss of sensor reference voltage or ground
- Water or contamination in connector
- ECM input fault or internal short
Symptoms
- Check Engine Light (CEL) illuminated
- Reduced drivability or limp mode on some vehicles
- Incorrect fuel trims (high or low) and rough idle
- Poor starting or reduced engine performance at altitude
- Possible hard starting when ambient pressure is low or changes rapidly
What to check
- Retrieve freeze frame and live data for BARO sensor value and compare to known ambient pressure (weather station or handheld barometer).
- Check for related MAP/BARO codes (P0105–P0109, P2227).
- Visually inspect BARO sensor, connector, and wiring for damage or corrosion.
- Backprobe sensor signal, reference 5 V, and ground at key ON engine OFF and at idle.
- Measure resistance/continuity between sensor ground and engine ground/ECM ground.
- Wiggle test harness while monitoring live sensor voltage for intermittent faults.
Signal parameters
- Typical BARO sensor signal: ~0.5 V to ~4.5 V across atmospheric range (varies by design).
- Expected ambient pressure voltage at sea level commonly ~1.0–2.5 V (vehicle dependent).
- Circuit low fault usually triggered when signal < ~0.2–0.4 V or near 0 V.
- Reference supply usually 5 V (check nominal 4.8–5.2 V at sensor reference pin).
- Sensor ground should be near 0 V (within a few hundred millivolts).
Diagnostic algorithm
- Connect a scan tool and record freeze frame, live BARO value, MAP (if present) and fuel trims. Note when code set and any driving conditions.
- Visually inspect the sensor and harness for damage, rodent chew, corrosion, or water ingress. Repair obvious issues.
- With ignition ON (engine OFF), backprobe the sensor connector: verify reference voltage (~5 V), signal voltage, and ground continuity. If reference voltage missing or low, suspect ECM circuit or fused supply.
- If reference and ground OK but signal is low (
- Perform a wiggle test on wiring while monitoring live data to find intermittent shorts or opens.
- If wiring checks OK, bench-test or substitute a known-good BARO sensor and re-check signal. If replacement clears the fault, replace sensor.
- If new sensor does not restore signal, trace and repair wiring back to ECM; check for proper ECM pin voltages and possible internal ECM fault.
- After repairs, clear codes and perform a drive cycle to confirm the fault does not return and that BARO reading matches expected ambient pressure.
Likely causes
- Signal wire shorted to ground at a connector or harness chafe point
- Damaged sensor (internal short or failed electronics)
- Loose, corroded, or pushed-out terminals at harness connector
- Missing or low 5 V reference supply from ECM
- Intermittent wiring fault exposed by movement or temperature change
Fault status
Status
Barometric Pressure Sensor A Circuit Low — low or missing BARO sensor signal detected. Check sensor, wiring, 5 V reference and ground.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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