P005F

Turbocharger/Supercharger Boost Control B Supply Voltage Circuit High

P005F is a generic OBD-II powertrain diagnostic trouble code: Turbocharger/Supercharger Boost Control B Supply Voltage Circuit High. It is logged by the engine control unit when the turbo/boost monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P005F
Group
Powertrain
System
Turbo/Boost
Severity
Warning (MIL on, possible limp mode)
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What P005F means

Code P005F is a generic SAE powertrain code set when the Powertrain Control Module (PCM) detects an abnormally high supply voltage in the turbocharger or supercharger boost control 'B' circuit. The boost control solenoid regulates the amount of pressurised air delivered to the intake manifold by modulating wastegate or bypass valve position. The PCM continuously monitors the voltage signal on this control circuit and compares it to calibrated thresholds; when the measured voltage remains above the acceptable upper limit for a set period, a fault is logged and the Malfunction Indicator Lamp is illuminated. A high-voltage condition on the boost control circuit typically indicates a short to a voltage source in the wiring, a failed solenoid driver, or an open ground path that forces the signal line high. Because the PCM cannot reliably regulate boost pressure under this fault condition, it may reduce commanded boost to protect the engine and catalytic converter, resulting in noticeable power loss. Left unaddressed, uncontrolled boost can accelerate wear on turbocharger bearings, pistons, and head gaskets.

Common causes

Most-frequently reported root causes when P005F is logged.

  • 1
    Wiring harness short to battery positive voltage between the PCM and boost control solenoid 'B'
  • 2
    Faulty or internally shorted boost control solenoid 'B'
  • 3
    Corroded, damaged, or backed-out connector pins at the boost solenoid or PCM
  • 4
    Open ground circuit for the boost control solenoid causing the signal line to float high
  • 5
    Failed PCM boost-control output driver producing incorrect voltage
  • 6
    Chafed wiring contacting chassis ground or adjacent 12V power lines near the turbocharger
  • 7
    Water or coolant intrusion into the solenoid connector causing resistance changes

Symptoms drivers notice

Malfunction Indicator Lamp (check engine light) illuminated
Reduced engine power or activation of limp/safe mode
Noticeable turbo lag or lack of boost response under acceleration
Rough idle or hesitation at low RPM due to incorrect air delivery
Possible overboost or underboost condition depending on solenoid default state

How to diagnose P005F

A typical diagnostic flow when this code is present.

  1. 1
    Connect an OBD-II scanner, retrieve all stored codes, and record freeze frame data to identify operating conditions when P005F was set
  2. 2
    Visually inspect the boost control solenoid 'B' wiring harness for chafing, heat damage, or contact with exhaust components; examine connector pins for corrosion or push-back
  3. 3
    With ignition on and solenoid unplugged, measure voltage on the signal wire at the harness connector — a reading above specification (typically >5V reference) confirms a short to power
  4. 4
    Using a digital multimeter, measure solenoid coil resistance across the two heater terminals; compare against manufacturer specification (commonly 10–20 Ohms); replace solenoid if out of range
  5. 5
    Verify ground circuit continuity from the solenoid ground pin back to the PCM ground with resistance under 1 Ohm
  6. 6
    Clear stored codes, perform a test drive under boost conditions, and confirm whether P005F resets; if it does, proceed to PCM pin-level voltage testing per the OEM wiring diagram
  7. 7
    Check for any applicable Technical Service Bulletins related to the boost control circuit before authorising PCM replacement

Related powertrain codes

Frequently asked questions

Is it safe to drive with code P005F active?

Short trips to a repair facility are generally tolerable, but extended driving is not recommended. The PCM may restrict boost to protect the engine, causing significant power loss, and uncontrolled boost events can damage the turbocharger, pistons, or head gasket over time.

Will clearing the code fix the problem?

No. Clearing the code removes the MIL temporarily, but if the underlying electrical fault — such as a wiring short or failed solenoid — is not repaired, the PCM will detect the abnormal voltage again within one or two drive cycles and reset the code.

Can a bad boost solenoid cause P005F?

Yes. An internally shorted solenoid winding can pull the signal line toward supply voltage. Testing solenoid coil resistance with a multimeter is one of the first component-level checks to perform.

Could the PCM itself be causing P005F?

A failed PCM boost-control output driver is possible but rare. Always rule out wiring shorts, connector corrosion, and a faulty solenoid before condemning the PCM, as PCM replacement is expensive and misdiagnosis is common with circuit-high codes.

Disabling P005F in software

RaceTune can permanently disable P005F — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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