P0117 fault code: Engine Coolant Temperature Circuit Low

P0117 means “Engine Coolant Temperature Circuit Low” — a fuel and air metering fault in the powertrain.

Can I DIY?

Professional-only boundary. Do not open a hot cooling system; confirm P0117 and book a garage.

Do not DIYReviewed page boundary
ToolsSpecialist equipment

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 P0117

Do not drive. The coolant-temperature circuit is reading too low, which can keep the engine in a false cold-start map even after it is actually warm — or hide a real overheat if the signal is simply wrong.

Take these reviewed, code-specific details with you. They help the garage confirm the fault without turning this page into a repair procedure.

  • Engine Coolant Temperature Circuit Low: Registration number
  • Engine Coolant Temperature Circuit Low: Exact code P0117 and whether the gauge looked low, normal, or high
  • Engine Coolant Temperature Circuit Low: Any steam or coolant on the ground
  • Engine Coolant Temperature Circuit Low: Whether the cabin heater stayed cold after a proper run
P01xxFuel and air metering
MOT fail riskif the warning light stays on

What does P0117 mean?

P0117 is a generic (SAE standard) powertrain code reported by your car’s engine control unit. It sits in the P01xx block, which covers fuel and air metering. The stored description is “Engine Coolant Temperature Circuit Low”. The code itself tells you which circuit or system tripped the fault — not always the exact part that failed.

Will P0117 fail an MOT?

An illuminated engine management light is a Major defect at MOT until repaired and the lamp stays off. P0117 is a low coolant-temperature circuit; MOT testers still fail a leaking or overheating cooling system on sight.

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

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. Car overheating but coolant looks full: stop and recoverNo — do not continue driving while the engine is overheating, even if the expansion bottle looks full. Move only far enough to reach a place of relative safety, switch off, and… Coolant keeps disappearing with no visible leakA falling cold level still means coolant is escaping; never open a hot pressurised system.
P0100Mass or Volume Air Flow Circuit P0101Mass or Volume Air Flow Circuit Range/Performance P0102Mass or Volume Air Flow Circuit Low Input P0103Mass or Volume Air Flow Circuit High Input P0104Mass or Volume Air Flow Circuit Intermittent P0105Manifold Absolute Pressure/Barometric Pressure Circuit P0106Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance P0107Manifold Absolute Pressure/Barometric Pressure Circuit Low Input

P0117 — quick answers

Is it safe to drive with P0117?

Do not drive. We have no verified driving guidance for P0117 — treat as do not drive until checked. A low coolant-temp circuit can lie; if you see steam or a red warning, stop regardless of this code.

Will P0117 fail my MOT?

An illuminated engine management light is a Major defect at MOT until repaired and the lamp stays off. P0117 is a low coolant-temperature circuit; MOT testers still fail a leaking or overheating cooling system on sight.

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.