P0039 fault code: Turbo/Super Charger Bypass Valve Control Circuit Range/Performance
We have no verified driving guidance for P0039. Do not drive until bypass-valve range/performance is checked. Stop if boost noise is harsh or power comes in a sudden spike.
Can I DIY?
Professional-only boundary. You can read P0039; range/performance on the bypass valve is not DIY.
This is the conservative boundary from the reviewed code record. This page has no frozen site-wide safety grade, so it does not publish a repair route.
What to tell the garage about P0039
Do not drive until checked. The turbo or supercharger bypass valve is not responding in the expected range. The computer sees a performance mismatch on that valve, not a simple heater open and not swapped oxygen signals.
Take these reviewed, code-specific details with you. They help the garage confirm the fault without turning this page into a repair procedure.
- Turbo/Super Charger Bypass Valve Control Circuit Range/Performance: Registration number
- Turbo/Super Charger Bypass Valve Control Circuit Range/Performance: Exact code P0039 and any companion codes
- Turbo/Super Charger Bypass Valve Control Circuit Range/Performance: Whether the engine management light is steady or flashing
- Turbo/Super Charger Bypass Valve Control Circuit Range/Performance: Boost feel: lag, spike, or flutter, if you noticed any
What does P0039 mean?
P0039 is a generic (SAE standard) powertrain code reported by your car’s engine control unit. It sits in the P00xx block, which covers fuel and air metering. The stored description is “Turbo/Super Charger Bypass Valve Control Circuit Range/Performance”. The code itself tells you which circuit or system tripped the fault — not always the exact part that failed.
Will P0039 fail an MOT?
An illuminated engine management light is a Major defect at MOT (automatic fail) until the fault is repaired and the light stays off. P0039 does not change that lamp rule.
Before booking your test, check what usually fails on your car: see our MOT pass rates by make and model, built from 33.1 million DVSA tests.
Related guides
Related fault codes
P0039 — quick answers
Is it safe to drive with P0039?
Do not drive until checked. We have no verified driving guidance for P0039. Do not drive until bypass-valve range/performance is checked. Stop if boost noise is harsh or power comes in a sudden spike.
Will P0039 fail my MOT?
An illuminated engine management light is a Major defect at MOT (automatic fail) until the fault is repaired and the light stays off. P0039 does not change that lamp rule.
Fault-code identifiers are standard diagnostic facts. Their explanations and diagnostic guidance on this site are original editorial summaries, not reproduced SAE wording. MOT defect rules reflect the DVSA MOT inspection manual (2026). This page is general guidance for UK drivers, not a substitute for a professional diagnosis.