Loose, corroded or damaged connector at the ECT sensor; Failing ECT sensor with an internal intermittent open circuit; Chafed, broken or high resistance wiring in the sensor signal or ground circuit; Poor sensor ground or reference supply connection at the control module; Faulty connector pins or terminals at the engine control module; Faulty engine control module.

P1115

Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage IAT - B Circuit High Input.

Ford
Powertrain
Manufacturer code
Medium severity

How this code is built

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

What it means

On Ford vehicles P1115 means the engine control module has seen an intermittent high voltage signal on the engine coolant temperature (ECT) sensor circuit, with the related IAT B circuit also listed in the definition. A high voltage reading usually points to an open circuit or high resistance in the sensor or its wiring, and because it comes and goes the fault may not be present all the time. Exact sensor layout and which circuits are involved vary by model and engine, so check the manufacturer wiring information for the vehicle.

Symptoms

Malfunction indicator lamp on
Hard or long cranking when starting, especially from cold
Rough or unstable idle
Poor fuel economy or rich running
Cooling fans running constantly or at odd times
Temperature gauge reading erratically or dropping to cold

Possible causes

Loose, corroded or damaged connector at the ECT sensorlikely
Failing ECT sensor with an internal intermittent open circuitlikely
Chafed, broken or high resistance wiring in the sensor signal or ground circuitpossible
Poor sensor ground or reference supply connection at the control modulepossible
Faulty connector pins or terminals at the engine control modulerare
Faulty engine control modulerare

How to diagnose

Read all stored and pending codes and note the freeze frame data, including coolant temperature and engine load at the time the fault set
Check the live coolant temperature reading with the engine cold; it should be close to ambient and rise smoothly as the engine warms, with no sudden jumps or readings stuck at an extreme low
Inspect the ECT sensor connector and wiring for corrosion, bent or pushed-back pins, damaged insulation and rubbing points
With the engine running, wiggle the connector and harness while watching live coolant temperature for sudden changes
Check the sensor reference voltage and ground at the connector against the manufacturer wiring data
Measure the sensor resistance at different temperatures and compare it with the manufacturer specification
Test the signal wire for continuity and for high resistance back to the control module
Check the connector pins at the control module and review any relevant technical service information for the model

How to fix

Clean, re-seat or replace the ECT sensor connector and any damaged terminals
Replace the ECT sensor if its resistance is out of specification or it fails the wiggle test
Repair or replace damaged wiring in the signal or ground circuit
Repair poor ground or reference supply connections
Repair or replace the engine control module connector terminals if they are faulty
Replace or reprogram the engine control module only after all wiring and sensor faults are ruled out and the manufacturer procedure calls for it

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but fix it soon because the control module may be using wrong temperature data, causing poor starting, rich running and fan problems. Keep an eye on the real engine temperature, as the gauge may not be reliable.

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