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GTECH Calibration
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P1116

ECT Signal Unstable Or Intermittent.

  • Chrysler
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
1
AreaFuel and air metering
16
FaultThe specific fault in that area

What it means

On Chrysler vehicles P1116 means the engine control unit has seen the engine coolant temperature (ECT) sensor signal behave unstably or drop in and out, rather than changing smoothly as the engine warms. The signal may jump, spike or disappear for a moment, or may not match the temperature the control unit expects. Exact setting criteria vary by model and engine, so check the manufacturer data for the vehicle.

Symptoms

  • Check engine light on
  • Hard or extended cranking when starting, especially from cold
  • Rough idle or hunting idle
  • Poor fuel economy or a rich-running smell
  • Cooling fan running at odd times or constantly
  • Temperature gauge reading erratically or incorrectly

Possible causes

  • Failing coolant temperature sensor with an intermittent internal faultlikely
  • Loose, corroded or contaminated sensor connector terminalslikely
  • Chafed, broken or intermittently open wiring between the sensor and the control unitpossible
  • Poor sensor reference or ground connection shared with other sensorspossible
  • Low coolant level or air in the cooling system leaving the sensor exposed to air pocketspossible
  • Fault in the engine control unit input circuitrare

How to diagnose

  1. Read all stored and pending codes and note the freeze frame data, including coolant temperature and engine load when the code set.
  2. Check the coolant level when the engine is cold and look for leaks or signs of air in the system.
  3. Inspect the sensor connector and wiring for damage, corrosion, water ingress, heat damage or chafing, and check the terminals fit tightly.
  4. With a scan tool, watch live coolant temperature from a cold start and look for sudden jumps, dropouts or a reading that stalls.
  5. Wiggle the connector and harness with the engine running while watching live data to see if the reading glitches.
  6. Compare the live coolant temperature with a trusted reading, such as an infrared thermometer on the housing, to check plausibility.
  7. Measure the sensor resistance at different temperatures and compare with the manufacturer specification for the engine.
  8. Check the sensor circuit for continuity, short to earth, short to voltage and reference and ground integrity as per the wiring diagram.

How to fix

  • Replace the coolant temperature sensor if its readings are erratic or out of specification.
  • Clean, repair or replace the connector and terminals if corroded or loose.
  • Repair or replace damaged wiring in the sensor circuit.
  • Top up and bleed the cooling system correctly, and fix any leak causing low coolant or air ingress.
  • Repair the reference or ground fault if found, and only consider the control unit after all other causes are ruled out.

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but fix it soon because wrong temperature data can cause poor running, high fuel use and fan problems. If the temperature gauge shows overheating or the fan is not working properly, stop and have it checked.

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

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