P25F9

Code

Generic P — Powertrain

Turbocharger/Supercharger Bypass Valve C Control Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 19 EN: 37 RU: 23

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Short to ground on the bypass valve C control circuit
Open or damaged wiring / connector corrosion
Faulty bypass (bypass/recirculation/wastegate) valve C (stuck or shorted coil)
Poor power supply or ground at the valve connector
Faulty ECM/PCM driver (rare)
Related sensor faults or mechanical turbo/supercharger issues affecting drivability

Scan for P25F9 and any related codes; review freeze frame/live data
Verify vehicle history: intermittent vs. permanent code, recent repairs
Visually inspect wiring and connectors at bypass valve C and along harness for damage, corrosion, or rubbing
Backprobe the bypass valve connector and measure voltage with key ON and while commanding the valve
Measure resistance of the bypass valve coil with connector disconnected (compare to spec)
Check for proper power supply (12 V) and ground continuity to the valve

Typical solenoid coil resistance (varies by vehicle): approx. 5–40 ohms (refer to OEM spec)
Key ON, engine OFF: supply feed to valve typically near battery voltage (~11–14 V)
When PCM/ECM grounds the valve to operate: control side may be pulled near 0 V (or modulated duty 0–12 V depending on driver type)
When valve is not commanded: control circuit voltage typically near supply voltage (~12 V) if driver switches to ground, or near 0 V if driver switches to +12 V (refer to model-specific wiring)
A 'low' fault generally means measured voltage is below expected threshold when the circuit should be at supply voltage or at expected commanded level

Retrieve freeze frame and related codes; clear codes and attempt to re-run to reproduce.
Visually inspect the bypass valve C connector and harness for damage, corrosion, pin push-out, or water ingress. Repair any obvious damage.
Backprobe the valve connector with key ON, engine OFF. Verify supply voltage at the power terminal (~12 V). If supply is missing, trace and repair the supply feed/fuse.
Command the bypass valve ON via a bidirectional scan tool while monitoring the control terminal voltage. Note whether the voltage changes as expected or remains low.
With the connector disconnected, measure valve coil resistance. Compare to OEM spec. If coil resistance is extremely low (near short) or open/infinite, replace the valve.
Check continuity from the ECM/PCM control pin to the valve connector. Look for shorts to ground (resistance to chassis ground) and opens.
If suspecting intermittent short, perform wiggle tests on harness while monitoring live data or voltage. Use scope to inspect waveform for PWM noise or shorting.
If wiring and valve check good, test or substitute a known-good valve or temporarily apply regulated 12 V to the valve (bench test) to confirm operation — follow safety precautions.
If wiring and valve are good and fault persists, consider ECM/PCM driver fault. Confirm with manufacturer procedures before replacing ECM/PCM.
After repair, clear codes and road test to confirm the fault does not return and boost control is normal.