Code
P1451
PLYMOUTH
P — Powertrain
Barometric Pressure Sensor Performance
Views:
UK: 39
EN: 61
RU: 39
AI status
Completed
Completed
100%
Causes
- Failed or intermittent BARO sensor
- Damaged, corroded or disconnected wiring/connector to BARO sensor
- Short to voltage or ground in sensor circuit
- PCM software anomaly or internal PCM fault
- Blocked vent or contaminated sensor port (if externally vented)
- Mismatch between BARO and MAP readings due to vacuum/leak or MAP sensor fault
Symptoms
- Mil (Check Engine) lamp illuminated
- Poor idle quality or rough running
- Hard start or stalling in some conditions
- Reduced fuel economy or drivability issues
- Failed emissions test or elevated tailpipe emissions
What to check
- Retrieve freeze frame and live data with a scan tool; record BARO, MAP, and key engine-off MAP values
- Compare BARO sensor value to MAP sensor at key-on engine-off — they should be nearly equal
- Check for other related DTCs (MAP, intake temp, fuel trims)
- Visually inspect BARO sensor connector and wiring for damage or corrosion
- Measure sensor supply (reference) voltage and ground at connector with DVOM
- Backprobe sensor signal and confirm output is within expected range and changes with known pressure changes
Signal parameters
- Typical BARO sensor signal voltage range: approx. 0.5–4.5 V (varies by vehicle)
- Expected ambient pressure range reported by BARO: roughly 300–1100 hPa (30–110 kPa) or ~4.4–16 psi depending on altitude
- Reference voltage usually 5 V or 3.3 V from PCM; ground should be near 0 V
- BARO and MAP should be nearly equal with engine off / key on
Diagnostic algorithm
- Connect a capable scan tool, note DTCs, freeze frame and live BARO/MAP values.
- With ignition ON engine OFF, compare BARO value to MAP; if they differ significantly, suspect sensor or wiring.
- Inspect BARO sensor connector and harness for corrosion, bent pins, damaged insulation or water ingress; repair as needed.
- Measure reference voltage and ground at the sensor connector. If reference or ground out of spec, trace wiring to PCM and repair.
- Backprobe the sensor signal and observe voltage. Verify voltage changes appropriately with simulated pressure change (apply slight vacuum/pressure if serviceable) or change in altitude.
- If wiring and supply are good but signal is out of range or erratic, replace the BARO sensor and clear codes.
- After repair, perform key-on and engine-run checks and a road test; confirm BARO and MAP correlation and that the DTC does not return.
- If fault persists after replacing sensor and repairing wiring, consider PCM reflash or replacement as a last resort per factory procedures.
Likely causes
- Open or short in BARO sensor signal, reference or ground circuit
- Corroded connector pins or water intrusion at sensor
- Failed BARO sensor electronics
- MAP sensor reading inconsistent (causing correlation fault)
- Faulty PCM (least common)
Fault status
Status
Barometric Pressure Sensor Performance — PCM detected BARO sensor output out of expected range or not correlating with MAP/ambient pressure.
Repair difficulty: Medium
Diagnostic time: 1-2 hours
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