Engine Coolant Temperature Sensor Circuit Intermittent
The P0119 code indicates an intermittent fault in the engine coolant temperature (ECT) sensor circuit. The ECT sensor is a thermistor that changes resistance with temperature, and the PCM monitors its signal to adjust fuel mixture, ignition timing, and cooling fan operation. An intermittent signal can be caused by a loose or corroded connector, damaged wiring, or a failing sensor. This can lead to erratic engine behavior, poor fuel economy, and potential overheating if the cooling fans fail to activate properly.
01. Most Common Causes
- Loose or corroded electrical connector at the ECT sensor
- Damaged or chafed wiring in the sensor circuit
- Faulty ECT sensor (intermittent internal failure)
- Poor ground connection in the sensor circuit
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor fuel economy
- Engine running rich or lean
- Hard starting, especially when cold
- Cooling fans running continuously or not at all
- Temperature gauge reading erratic or incorrect
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data to capture conditions when the fault occurred.
Step 2: Visually inspect the ECT sensor connector and wiring for damage, corrosion, or loose connections.
Step 3: Check the sensor's resistance at different temperatures using a multimeter and compare to specifications.
Step 4: Wiggle the wiring harness while monitoring the sensor signal with a scan tool to reproduce the intermittent fault.
Step 5: If no issues found, replace the ECT sensor and clear the code.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive for extended periods as the intermittent signal can cause poor engine performance, reduced fuel economy, and potential overheating if the cooling fans malfunction.
How much does it cost to fix?▼
The typical repair cost ranges from $50 to $150, including parts (ECT sensor) and labor. DIY replacement is often simple and can save on labor costs.