P1114
SubaruEngine Coolant Temperature (ECT) Sensor Circuit Intermittent Low Voltage/IAT - B Circuit Low Input. This indicates the Powertrain Control Module (PCM) detected an intermittent low voltage signal from the Engine Coolant Temperature (ECT) sensor, suggesting an issue with the sensor or its circuit.
Medium SeverityThis code signifies that the Engine Coolant Temperature Sensor is sending an inconsistently low voltage signal to the engine computer, which can lead to incorrect fuel mixture and timing. Drivers may notice poor engine performance, reduced fuel efficiency, or difficulty starting the vehicle.
⚠️ Before You Begin (Safety First)
Always allow the engine to cool completely before working with cooling system components to prevent burns. When working with electrical components, disconnect the battery's negative terminal to avoid accidental shorts or electrical shocks.
Common Symptoms
- Check Engine Light illuminated
- Poor fuel economy
- Rough idle
- Hard starting, especially when cold
- Engine running rich (excessive fuel consumption)
- Engine running lean (not enough fuel)
- Engine overheating (less common, but possible if sensor reads too low)
Common Causes
- Faulty Engine Coolant Temperature (ECT) sensor
- Corroded or loose electrical connectors at the ECT sensor
- Damaged or shorted wiring in the ECT sensor circuit
- Intermittent open in the ECT sensor circuit
- Faulty Powertrain Control Module (PCM) (rare)
Frequently reported on: Subaru Impreza 2008-2011, Subaru Forester 2009-2013, Subaru Outback 2005-2009, Subaru Legacy 2005-2009, Subaru WRX 2008-2014
Diagnostic Steps
- Locate the Engine Coolant Temperature (ECT) sensor (typically near the thermostat housing on the engine).
- Inspect the ECT sensor's electrical connector for corrosion, damage, or looseness. Clean or re-seat if necessary.
- Inspect the wiring leading to the ECT sensor for any signs of fraying, cuts, or pinched wires.
- With the engine cold, test the resistance of the ECT sensor using a multimeter. Compare the reading to the manufacturer's specifications (resistance should decrease as temperature increases).
- If the sensor's readings are out of specification or inconsistent, replace the ECT sensor.
- Clear the P1114 code using an OBD-II scanner and test drive the vehicle to confirm the repair.
👨🔧 When to Call a Professional
If after inspecting the wiring and replacing the Engine Coolant Temperature Sensor the code persists, or if you suspect a more complex electrical issue such as a short or open circuit within the vehicle's wiring harness, it's best to consult a professional mechanic.
Commonly Asked Questions
What is the primary function of the Engine Coolant Temperature (ECT) sensor?
The ECT sensor measures the temperature of the engine coolant and sends this data to the PCM, which uses it to adjust fuel delivery, ignition timing, and cooling fan operation for optimal engine performance.
Can I drive with a P1114 code?
While you can technically drive with this code, it's not recommended for extended periods. The incorrect temperature readings can lead to poor fuel economy, increased emissions, and potentially cause other engine components to wear prematurely.
How do I test the ECT sensor myself?
You can test the ECT sensor by measuring its electrical resistance with a multimeter while the engine is cold and then again after it warms up. The resistance should decrease as the engine coolant temperature rises. You'll need your vehicle's service manual for specific resistance values at different temperatures.
What tools do I need to replace the ECT sensor?
Typically, you'll need a wrench or socket set to remove the old sensor, a new ECT sensor, a bucket or pan to catch any coolant, and possibly pliers for hose clamps. Ensure you have the correct size wrench for your specific sensor.
Will replacing the ECT sensor fix my Check Engine Light immediately?
After replacing the sensor, you will need to clear the P1114 code using an OBD-II scanner. If the repair was successful, the Check Engine Light should turn off and not return after driving the vehicle for a short period.