P004D
- Powertrain
- Generic (SAE)
- Emissions
Get it looked at now
Driving may cause further damage or leave you stranded. Arrange service promptly rather than waiting.
Turbocharger/Supercharger Boost Control B Circuit High
This code is in our catalogue but has not yet been through editorial review, so the guidance below is limited to what our structured data supports. We publish deeper diagnostic content only after a code has been reviewed — here is why.
Boost control B circuit voltage above expected range. Same as P0048 on actuator B. Boost control tracks commanded vs. actual manifold pressure; persistent deviation means wastegate, vanes, hose or actuator are not delivering the requested pressure.
A trouble code records what a control module measured. It does not identify which part failed. Test before replacing anything.
- Safe to drive
- Driving may cause further damage or leave you stranded. Arrange service promptly rather than waiting.
- Urgency
- Get it looked at now
- Will it pass emissions
- No
- Check engine light
- Solid
- Clearing the light
- A completed drive cycle is normally required before the monitor re-runs and the light can clear.
- Charge status indicator shows fault
- Charging may not start or interrupts
- Slower-than-expected charge rate
Many vehicles show no symptom at all beyond the warning light. The absence of a symptom does not mean the fault is not real.
| # | Cause | How often | Component |
|---|---|---|---|
| 1 | Wiring shorted to battery | Very common | — |
| 2 | Connector pins corroded - high contact resistance | Occasional | — |
| 3 | Supply wire pinched against B+ source | Occasional | — |
Ordering reflects how often each cause is responsible in general, not a probability for your vehicle. Confirm by testing.
- Boost Control Solenoid B
- Actuator Wiring
- Definition
- Generic code set (SAE J2012 / ISO 15031-6) via the OBDexopen database, dedicated to the public domain under CC0-1.0.
- Diagnostic guidance
- Written and reviewed in-house. See our editorial policy.
- Review status
- Awaiting review
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