Code
P227B
Generic
P — Powertrain
Barometric Pressure Sensor C Circuit Range/Performance
Views:
UK: 18
EN: 40
RU: 29
AI status
Completed
Completed
100%
Causes
- Open, shorted, or corroded wiring/connectors between the BARO sensor and PCM
- Faulty BARO sensor (internal electronics failed or intermittent)
- Poor sensor reference voltage (5 V) or poor ground at the sensor
- Intermittent connector contact (corrosion, bent pins, water intrusion)
- PCM input fault or internal module intermittent
- Software calibration or configuration error (rare)
Symptoms
- Check Engine Light (MIL) illuminated
- Engine may run poorly at idle or during transitions (hesitation, stumble)
- Poor fuel economy or drivability complaints
- Reduced engine performance or limp-home mode (depending on vehicle strategy)
- Difficulty starting or altered idle speed under different altitudes
What to check
- Read and record freeze frame and all stored codes with a capable scan tool
- Verify whether BARO reading is present and stable in live data (key ON and engine OFF and engine running)
- Compare BARO sensor value to MAP sensor and expected ambient pressure (local atmospheric pressure)
- Visually inspect sensor connector for corrosion, bent pins, damaged seals, or water intrusion
- Backprobe sensor connector: check for reference voltage (~5 V) and good ground
- Wiggle harness while monitoring live data to reproduce intermittent faults
Signal parameters
- Reference voltage (Vref): typically 5.0 V ±0.25 V (verify vehicle spec)
- Signal output: commonly ~0.5–4.5 V proportional to absolute pressure (sensor-specific calibration)
- At sea level baro voltage often in a mid-range; expect a stable, reasonable voltage matching local atmospheric pressure (compare to known sea-level/mountain altitudes)
- No output or steady 0 V suggests open or no Vref/ground; near Vref (≈5 V) suggests short to 5 V or sensor stuck high
- Rapid voltage spikes, noise, or intermittent jumps indicate wiring/connector or internal sensor fault
Diagnostic algorithm
- Verify the DTC: Connect a scan tool, record freeze frame and any other stored codes. Note whether the code is current or historic and whether it is intermittent.
- Reproduce fault: Clear codes, monitor BARO sensor C data while cycling ignition and during engine operation to see if the code returns.
- Compare sensors: With key ON (engine OFF) and engine running, compare BARO reading to MAP and to known ambient pressure (weather report or handheld barometer). BARO should not conflict significantly with MAP when the engine is off.
- Visual inspection: Inspect BARO sensor and harness for damage, corrosion, moisture, or loose pins. Repair any obvious connector/harness damage.
- Electrical checks: Backprobe connector. Verify reference voltage (≈5 V) and ground. Measure sensor output voltage and observe its stability while varying altitude simulator (if available) or applying vacuum/pressure if service manual recommends.
- Wiggle test: With live data streaming, wiggle the wiring harness and connector to check for intermittent faults that reproduce voltage jumps or DTC set.
- Check for shorts/opens: Use a multimeter to check continuity from sensor pins to PCM pins, and check for short to battery voltage or ground. Repair any wiring faults found.
- Sensor substitution: If wiring and reference/ground are good and output is out-of-range or unstable, replace the BARO sensor (or MAP assembly if BARO is integrated) with a known-good unit and retest.
- PCM/software: If replacement sensor and wiring check OK and code persists, check for PCM updates/TSBs. Consider PCM input diagnostics or replacement per manufacturer guidance.
- Final verification: Clear codes and perform a road/test cycle to ensure code does not return and vehicle drivability is restored.
Likely causes
- Damaged or corroded wiring or connector at the BARO sensor
- Failed BARO sensor
- Loss of sensor reference voltage (open 5 V supply) or poor ground
Fault status
Status
Barometric Pressure Sensor C Circuit Range/Performance — PCM detected sensor output outside expected range, inconsistent with other inputs, or unstable. Inspect sensor circuit, wiring, connector, and sensor.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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