P25F2

Code

Generic P — Powertrain

Turbocharger/Supercharger Boost Sensor C Circuit

Brand: Generic

Type: P — Powertrain

Views: UK: 20 EN: 37 RU: 27

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open or short in the boost sensor C wiring or connector
Corroded or loose connector pins at the sensor or PCM
Failed boost/pressure sensor (internal short or drift)
Bad sensor reference voltage or ground at the PCM
Intake tract leak, stuck bypass/wastegate or actuator fault causing implausible readings
PCM/ECM internal fault or software issue (less common)

Symptoms

Malfunction indicator lamp (MIL) illuminated
Reduced engine power or limp-home mode
Poor acceleration or hesitation under boost
Unstable idle if sensor affects fuel/air control
High or low measured boost vs expected (when viewed in scan tool)

What to check

Retrieve freeze-frame and live data for boost sensor C and related sensors (MAP, MAF, boost actual vs target)
Check for other stored codes (MAP/boost/supercharger/turbocharger)
Visually inspect sensor C connector and wiring for damage, corrosion, loose pins, or water
Backprobe sensor connector and verify reference voltage (typically 5 V), signal voltage and ground
Wiggle harness with engine running to check for intermittent faults
Pressure-test intake system for leaks; inspect intercooler and hoses

Signal parameters

Typical sensor type: absolute/boost pressure sensor (voltage output proportional to pressure)
Reference voltage: ~5.0 V (verify with vehicle spec)
Signal voltage at atmospheric/low boost: ~0.5–1.5 V (varies by sensor)
Signal voltage at moderate/high boost: ~2.0–4.5 V (varies by sensor)
Expected sensor resistance: check service manual for sensor-specific values
If open circuit: signal near 0 V or floating; if short to 5 V: near 5 V; if short to ground: near 0 V

Diagnostic algorithm

Connect a professional scan tool, record freeze frame, and note whether the code is current or historic. Check for related codes (MAP, boost, turbo control).
Visually inspect the boost sensor C connector, wiring harness, and sensing port for damage, corrosion, or contamination. Repair or clean as needed.
With connector connected, backprobe the sensor harness and verify reference voltage (pin), signal voltage (pin) and ground continuity to chassis/ECM ground. Compare to vehicle specifications.
With engine off, measure resistance of sensor (if specified) or disconnect sensor and check for short to ground or battery on the signal circuit (use multimeter).
Start engine and monitor live data for sensor C while applying boost (rev or road test on a safe lift). Compare sensor C output to another MAP/boost sensor or an external boost gauge. Look for plausibility and response time.
Wiggle the harness and connectors while monitoring the signal to check for intermittent faults. Repair any chafing or broken conductors.
If wiring, grounds and reference voltage are good, apply a known pressure with a hand pump (or use vehicle boost) to the sensor while observing the signal output. Replace the sensor if output does not change correctly.
Inspect intake system for leaks, stuck bypass valves, wastegate or actuator faults that could make the signal appear implausible; repair as needed.
After repairs, clear codes, perform a test drive or reproduce the operating conditions and verify the code does not return. If code persists and wiring verifies correct, consider ECM/PCM diagnosis or replacement only after elimination of all external causes.

Likely causes

Damaged chafed wire to boost sensor C (pin short to ground or battery)
Water intrusion/corrosion at sensor connector
Failed boost pressure sensor C element
Blown sensor fuse or intermittent ground
Sensor mounting in incorrect location or blocked sensing port

Fault status

⚠️ Status

P25F2 - Turbocharger/Supercharger Boost Sensor C Circuit: ECM detected an open, short, or implausible signal from Boost Sensor C. May set MIL and cause reduced power or limp mode until repaired.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours