P0118 — Engine Coolant Temperature Sensor Circuit High
What it means: Engine Coolant Temperature Sensor Circuit High.
How serious / can you keep driving: Caution. Limp to the next safe stop.
Check first: Measure sensor resistance at operating temp
Don't risk it — look up listed providers near you and give them this code when you call.
Listed providers nearest Billings, MT
Closest first. Tell them P0118 and what the truck is doing. RoadService.app lists these providers and does not employ them or carry out the repair.
- 0.0 mi away — based in Billings, MT · (406) 245-8985
- 0.0 mi away — based in Billings, MT · (406) 252-8413
- 0.0 mi away — based in Billings, MT · (406) 780-3711
Seen on: Heavy Truck
What P0118 means
Engine Coolant Temperature Sensor Circuit High. Common causes: ECT sensor open circuit.
How serious is it?
Caution. Limp to the next safe stop.
Most likely causes
- ECT sensor open circuit
- Broken wire
- failed sensor
First moves (roadside)
- Measure sensor resistance at operating temp
- should be 150-300 ohm
- replace if open
FAQ
Engine Coolant Temperature Sensor Circuit High. Common causes: ECT sensor open circuit.
Caution — Limp to the next safe stop.
The most common cause is: ECT sensor open circuit. Other possibilities include Broken wire; failed sensor.
Limp to the next safe stop. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Related codes
Codes that commonly appear alongside P0118, or share the same subsystem.
- Coolant level — low (SPN 111 FMI 1)
- Engine Coolant Temperature — Too High (SPN 110 FMI 0)
- Coolant temp sensor — voltage high (SPN 110 FMI 3)
- Coolant temp sensor — voltage low (SPN 110 FMI 4)
- Coolant temperature — moderately high (SPN 110 FMI 16)
- Engine Coolant Over-Temperature Condition (P0217)
- Coolant Thermostat Below Regulating Temperature (P0128)
- Fan 1 Control Circuit Malfunction (P0480)
Same symptom: Running hot
Other codes that show up as coolant temperature climbing or a hot-engine lamp.
- Engine Coolant Temperature Sensor 1 Circuit (P0115) · Cooling
- Engine Coolant Temperature Sensor Range (P0116) · Cooling
- Engine Coolant Temperature Sensor Circuit Low (P0117) · Cooling
- Engine Coolant Temperature Sensor Intermittent (P0119) · Cooling
- Fan drive — voltage high (SPN 647 FMI 3) · Engine
- Fan drive voltage low (SPN 647 FMI 4) · Engine
Find a mechanic or related guides
General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.