P1117
HondaThe Engine Control Module (ECM) detects an intermittent signal from the Engine Coolant Temperature (ECT) Sensor, indicating a temporary or inconsistent fault in the sensor's readings, specific to Honda vehicles.
Medium SeverityThis code indicates that the Engine Coolant Temperature (ECT) Sensor is sending an inconsistent or intermittent signal to the vehicle's computer. This can lead to incorrect fuel mixture, affecting engine performance and fuel efficiency, and potentially causing the engine to run too rich or too lean.
⚠️ 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 engine components. Disconnect the battery's negative terminal before performing any electrical work. Be mindful of hot engine parts and rotating fans when the engine is running for diagnosis.
Common Symptoms
- Check Engine Light illuminated
- Poor fuel economy
- Engine running rough or stalling, especially when cold
- Erratic temperature gauge readings
- Failure to start in cold weather
- Cooling fans running constantly
Common Causes
- Faulty or intermittently failing Engine Coolant Temperature (ECT) Sensor
- Corroded or loose electrical connection at the ECT sensor
- Damaged or frayed wiring in the ECT sensor circuit
- Low engine coolant level (though less common for intermittent signal)
- Faulty thermostat (can indirectly affect readings)
Frequently reported on: Honda Civic (2001-2015), Honda Accord (2003-2017), Honda CR-V (2002-2016), Honda Odyssey (2005-2010)
Diagnostic Steps
- Use an OBD-II scanner to confirm the P1117 code and check for other related codes. Clear the code after recording it.
- Visually inspect the ECT sensor connector and wiring for any signs of corrosion, damage, or loose connections. Secure or clean as necessary.
- With the engine cool, locate the ECT sensor (typically near the thermostat housing or on the engine block/cylinder head). Have a drain pan ready as some coolant will spill.
- Carefully disconnect the electrical connector from the sensor. Use a wrench or socket to remove the old sensor.
- Install the new ECT sensor, ensuring the O-ring is properly seated. Tighten it to specification, but do not overtighten. Reconnect the electrical connector.
- Top off the engine coolant to the correct level and bleed any air from the cooling system according to your vehicle's service manual.
- Start the engine, monitor for leaks, and allow it to reach operating temperature. Recheck for the P1117 code.
👨🔧 When to Call a Professional
If you have replaced the ECT Sensor and the P1117 code persists, or if you suspect a wiring harness issue, it's best to consult a professional mechanic for advanced diagnostics.
Commonly Asked Questions
What does an intermittent ECT sensor signal mean?
It means the sensor's electrical signal to the engine computer is not consistently stable, sometimes sending correct readings and sometimes incorrect or no readings at all, often due to a faulty sensor or poor connection.
Can I drive my Honda with a P1117 code?
While possible, it's not recommended for long periods as it can lead to poor fuel economy, increased emissions, and potentially engine damage if the engine runs too rich or lean consistently. Get it checked promptly.
Where is the ECT sensor located on a Honda?
On most Honda models, the Engine Coolant Temperature (ECT) Sensor is typically found screwed into the engine block, cylinder head, or near the thermostat housing. Its exact location can vary by model and year, so consult your vehicle's repair manual.
Is P1117 related to my car overheating?
An intermittent ECT sensor might cause inaccurate readings, potentially leading to the cooling fans not engaging correctly or the temperature gauge showing incorrect values, which could indirectly contribute to or mask an overheating issue.
Do I need to drain all the coolant to replace the ECT sensor?
Typically, you will only lose a small amount of coolant when replacing the sensor, so a full drain is usually not necessary. However, always have a drain pan ready to catch any spilled coolant and be prepared to top off the system afterward.