Skip to content
GTECH Calibration
Portal

P1117

Engine Coolant Sensor intermittent/ECT Sensor Intermittent.

  • Other
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
1
AreaFuel and air metering
17
FaultThe specific fault in that area

What it means

P1117 is a manufacturer-specific code, and for the general 'Other' make it is read as an intermittent engine coolant temperature (ECT) sensor signal. The control unit saw the sensor reading jump, drop out or go implausible for short periods, rather than staying steadily out of range. Other makes use this code for completely different faults, so confirm the make-specific definition before diagnosing.

Symptoms

  • Engine warning light on
  • Hard or long cranking when starting, especially from cold
  • Cooling fans running when the engine is cold, or at odd times
  • Erratic or jumping temperature gauge, or gauge dropping to cold
  • Rough idle, hesitation or poor fuel economy
  • Black smoke or rich running intermittently

Possible causes

  • Faulty ECT sensor with an internal intermittent faultlikely
  • Loose, corroded or damaged connector at the ECT sensorlikely
  • Chafed, broken or intermittently shorting wiring between the sensor and control unitlikely
  • Poor sensor ground or reference voltage supply connectionpossible
  • Low coolant level or air pocket around the sensor causing erratic readingspossible
  • Fault within the engine control unit input circuitrare

How to diagnose

  1. Confirm the make and model, and check that the code definition for that manufacturer is an ECT sensor fault, as other makes use P1117 for different circuits.
  2. Read freeze frame data and any other stored codes, noting the coolant temperature and engine conditions when the fault set.
  3. Check the coolant level and condition, and look for signs of leaks or air in the system.
  4. Inspect the ECT sensor connector and wiring for corrosion, bent pins, chafing, heat damage or coolant contamination.
  5. Watch live ECT data from cold through warm-up while gently wiggling the connector and harness, looking for sudden jumps or dropouts.
  6. Compare the live ECT reading with a trusted temperature measurement of the engine, such as an infrared thermometer on the housing.
  7. Measure the sensor resistance at different temperatures and compare with the manufacturer's figures for that engine.
  8. Check the reference voltage and ground at the sensor connector, and test the wiring for continuity and shorts.

How to fix

  • Replace the ECT sensor if its readings are erratic or out of specification, after the system has been depressurised and cooled.
  • Repair or replace damaged wiring and clean or renew corroded connector terminals.
  • Restore a good ground or reference supply by repairing the affected circuit.
  • Top up and bleed the cooling system correctly, and repair any leak that caused low coolant.
  • Diagnose and, if proven faulty, repair or replace the control unit as a last resort.

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but fix it soon as wrong temperature data can cause poor starting, rich running and poor fuel economy. If the temperature gauge reads high or the engine appears to overheat, stop driving.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

This code for other makes

Nearby codes