P1116
SubaruEngine Coolant Temperature (ECT) Sensor Out of Self-Test Range
Medium SeverityThis code indicates that the Engine Coolant Temperature (ECT) sensor readings are outside the expected operating range during a self-test performed by the Engine Control Module (ECM). This can lead to incorrect fuel mixture, affecting engine performance, fuel economy, and potentially causing starting issues.
⚠️ Before You Begin (Safety First)
Always allow the engine to cool completely before working on the cooling system to prevent burns from hot coolant or steam. Disconnect the negative battery terminal before performing any electrical work. Be aware that pressurized cooling systems can release hot fluid. Wear appropriate eye protection.
Common Symptoms
- Check Engine Light illumination
- Poor fuel economy
- Engine running rich or lean
- Hard starting, especially when cold
- Erratic temperature gauge readings
Common Causes
- Faulty Engine Coolant Temperature (ECT) sensor
- Wiring harness issues (chafed, corroded, open, or shorted circuits)
- Poor electrical connection at the ECT sensor
- Low engine coolant level (less common for this specific range error)
- Faulty Engine Control Module (ECM) (rare)
Frequently reported on: Subaru Impreza (2005-2015), Subaru Forester (2006-2016), Subaru Outback (2007-2017), Subaru Legacy (2006-2014)
Diagnostic Steps
- Allow the engine to cool completely to avoid burns from hot coolant.
- Locate the Engine Coolant Temperature (ECT) sensor, usually near the thermostat housing or on the engine block.
- Disconnect the electrical connector from the ECT sensor.
- Inspect the connector and wiring for any signs of corrosion, damage, or loose connections.
- Using a wrench or a specialized sensor socket, carefully remove the old ECT sensor.
- Ensure the new sensor has the appropriate thread sealant or O-ring, and install it, tightening to manufacturer specifications.
- Reconnect the electrical connector securely.
- Top off the engine coolant if any was lost during the replacement.
- Start the engine, check for leaks, and ensure the Check Engine Light turns off after a few drive cycles, or clear the code with an OBD-II scanner.
👨🔧 When to Call a Professional
If replacing the ECT sensor does not resolve the P1116 code, or if additional diagnostic trouble codes (DTCs) related to the cooling system or electrical system appear, it is advisable to consult a certified mechanic for a more thorough diagnosis. Complex electrical issues or underlying engine problems may require specialized tools and expertise.
Commonly Asked Questions
Can I drive with P1116?
While you can drive, it's not recommended for long as it can lead to poor fuel economy, increased emissions, and potential engine issues due to incorrect fuel mixtures. Prompt repair is advised.
How do I test the ECT sensor?
You can test the ECT sensor's resistance with a multimeter. Disconnect the sensor, set the multimeter to ohms, and measure resistance across the sensor terminals. Compare this reading to the manufacturer's specifications for resistance at specific temperatures (e.g., cold vs. warm engine).
Is P1116 related to the thermostat?
Not directly. P1116 indicates an issue with the sensor's electrical signal or range, not necessarily the thermostat's mechanical operation. However, an incorrectly operating thermostat could indirectly affect the coolant temperature sensed by the ECT.
What if replacing the sensor doesn't fix P1116?
If replacing the sensor doesn't resolve the code, thoroughly inspect the wiring harness for damage, chafing, or corrosion, as well as the electrical connector for loose pins. If the wiring is good, the issue might be with the Engine Control Module (ECM), though this is a less common cause.
Where is the ECT sensor located on a Subaru?
On most Subaru models, the Engine Coolant Temperature (ECT) sensor is typically located on the engine block or cylinder head, often near the thermostat housing or in a coolant passage that is easily accessible.