Coolant temperature sensor high input on Ford — on EcoBoost engines that often means the cylinder head temperature sensor, not a coolant sensor at all.
Ford P0118 — Coolant temperature sensor high input on Ford — on EcoBoost engines that often means the cylinder head temperature sensor, not a coolant sensor at all. Typical UK independent garage cost: £40–£250.
What actually causes P0118 on a Ford
Many Ford petrol engines, including the 1.0 EcoBoost and Sigma family, don't use a traditional coolant temperature sensor. They use a cylinder head temperature (CHT) sensor screwed into the aluminium head. Some Ford ECUs log a CHT circuit fault under the coolant temperature codes, so the "P0118" a generic reader shows may really be a CHT circuit fault. That matters because a CHT sensor must never be reused once removed: it's a crush-fit design. On the 1.0 EcoBoost we also see the loom chafing near the coolant pipes. On TDCi diesels it's a conventional sensor in the thermostat housing, and corroded plugs are the usual story. Symptoms on a Ford are fans running on full, a cold-reading gauge, heavy fuel use and sometimes a rough cold start.
Ford engines that log P0118
- 1.0 EcoBoost (Fiesta, Focus, EcoSport, B-Max)
- 1.6 Ti-VCT Sigma (Fiesta, Focus)
- 1.5 / 2.0 TDCi EcoBlue (Focus, Kuga, Transit Custom)
- 1.6 / 2.0 TDCi Duratorq (Focus, Mondeo, Galaxy)
How we diagnose P0118 on a Ford
- Use a Ford-capable scan tool to confirm whether the fault is on the CHT or ECT circuit
- Compare the live temperature reading with a warm engine. An impossibly cold reading means an open circuit
- Inspect the loom from the sensor back towards the ECU, especially where it runs near the coolant pipes on the 1.0 EcoBoost
- Resistance test the sensor and check for 5V reference and earth at the plug
- Replace the sensor with a new part (never reuse a removed CHT sensor), clear the codes and road-test from cold
The common misdiagnosis to avoid
Chasing overheating that doesn't exist, or ordering the wrong sensor. Always confirm on a proper Ford-capable scanner whether the fault is the CHT or ECT circuit before buying parts. A generic reader just says P0118 either way. The other mistake is refitting the old CHT sensor after pulling it to inspect: it won't seal or read correctly again.
Ford P0118 repair cost in the UK
Expect £40–£250 including parts and labour at an independent garage. Main-dealer quotes on Ford are usually higher for the same job, and the spread exists because the cheap cause and the expensive cause throw the same code — pay for the diagnosis before you pay for parts.
Bob's workshop tip
Ford 1.0 EcoBoost: before you panic about coolant leaks, check it isn't simply the CHT sensor plug. If it is the sensor, it's a new one every time, no reusing.
Codes usually seen alongside P0118 on Ford
- P0117
- P1285
- P1299
- P0128
Symptoms drivers report with P0118
- The cooling fans running at full blast even when you've just started the car from cold.
- The car is a nightmare to start in the morning, chugging like an old tractor.
- The temp gauge on the dash is completely dead or jumping erratically.
- Black smoke out the back and a strong smell of unburnt petrol/diesel.
- The stop-start system has completely stopped working for no apparent reason.
Repairs that clear P0118
- Replace ECT sensor
- Repair wiring
For the generic, all-makes explanation of this code — meaning, every known cause and UK cost bands — see our P0118 guide.
Reading P0118 on a Ford properly
A generic reader will show P0118 and nothing else. What matters is the freeze-frame data stored with it — engine speed, load, coolant temperature and fuel trims at the moment the fault was logged — plus whether any other module on the Ford has logged something at the same time. Codes rarely arrive alone, and the order they were stored in usually points at which one is the cause and which are the consequences.
Clearing P0118 without fixing it
Erasing the code resets the Ford's readiness monitors as well as the light. The fault returns on the next drive cycle if the cause is still there, and in the meantime the incomplete monitors can stop the car passing an emissions check. After a genuine repair, the car is driven until the relevant monitor completes before it is handed back.
Bob's Mechanical Repairs is an independent garage in Birnam, Dunkeld, Perthshire, with 32 years of Bob's experience on the tools. If P0118 is showing on your Ford, bring any scan results with you — we will read the live data ourselves, confirm which cause it actually is, and price the repair before any work starts.