P0238 fault code: Turbo/Super Charger Boost Sensor 'A' Circuit High

Last updated · OBDCode UK editorial

Can I drive with P0238? — Limit driving

Limit driving. A high boost-sensor A signal can look like overboost to the computer. Stop if the engine bangs, the lamp flashes, or power surges.

P0238 means “Turbo/Super Charger Boost Sensor 'A' Circuit High” — a fuel and injector circuits fault in the powertrain. Limit driving. Boost sensor A is sitting too high on its voltage scale, which the computer treats as an implausible over-pressure report.

Can I DIY?

Caution — conditions apply. We do not publish DIY repair or strip-down steps for this code on this page. Read codes and observe only; leave the repair to a qualified garage.

Caution — conditions applyDIY boundary
ToolsBasic tools only — for example a household socket set, tyre gauge, or a consumer OBD reader.

Some checks may be possible for a careful DIY driver with the right tools and a safe place to work. Stop if anything feels beyond your skill or kit.

Hot systems

Never open a hot coolant cap — pressure can scald you. Exhaust and catalytic converter get hot enough to burn and ignite debris. Stay clear of electric fans; they can run after shut-off.

P02xxFuel and injector circuits
MOT fail riskif the warning light stays on

What does P0238 mean?

P0238 is a generic (SAE standard) powertrain code reported by your car’s engine control unit. It sits in the P02xx block, which covers fuel and injector circuits. The stored description is “Turbo/Super Charger Boost Sensor 'A' Circuit High”. The code itself tells you which circuit or system tripped the fault — not always the exact part that failed.

Will P0238 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. A lit lamp is a Major; this page does not invent an overboost MOT item.

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.

What the MOT data says

No MOT certificate item corresponds to this code; MOT outcome data cannot be shown.

Related guides

Car diagnostic test cost: compare the scopeUK booking marketplaces currently publish diagnostic averages of about £52–£65. Engine management light on: steady or flashing?A steady engine management light means the computer has stored a fault. Drive with caution and get the code read. A flashing light is different — stop when it is safe.
P0200Injector Circuit/Open P0201Injector Circuit/Open - Cylinder 1 P0202Injector Circuit/Open - Cylinder 2 P0203Injector Circuit/Open - Cylinder 3 P0204Injector Circuit/Open - Cylinder 4 P0205Injector Circuit/Open - Cylinder 5 P0206Injector Circuit/Open - Cylinder 6 P0207Injector Circuit/Open - Cylinder 7

P0238 — quick answers

Is it safe to drive with P0238?

Limit driving. Limit driving. A high boost-sensor A signal can look like overboost to the computer. Stop if the engine bangs, the lamp flashes, or power surges.

Can I fix P0238 myself?

Caution — conditions apply. We do not publish DIY repair or strip-down steps for this code on this page. Read codes and observe only; leave the repair to a qualified garage. Basic tools only — for example a household socket set, tyre gauge, or a consumer OBD reader.

Will P0238 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. A lit lamp is a Major; this page does not invent an overboost MOT item.

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.