P1117
ChryslerEngine Coolant Sensor intermittent/ECT Sensor Intermittent
Medium SeverityThis code indicates an intermittent signal from the Engine Coolant Temperature (ECT) sensor, meaning the Powertrain Control Module (PCM) is receiving inconsistent readings from it. This inconsistency can lead to incorrect fuel mixture adjustments, potentially causing poor fuel economy and erratic engine performance.
⚠️ Before You Begin (Safety First)
Always allow the engine to cool completely before working on any cooling system components to prevent severe burns. When checking electrical connections, consider disconnecting the vehicle's battery terminal to avoid accidental short circuits.
Common Symptoms
- Check Engine Light illumination
- Erratic or inaccurate temperature gauge readings
- Poor fuel economy
- Engine running rich or lean
- Rough idle or stalling
- Difficulty starting (especially in cold weather)
Common Causes
- Faulty or failing Engine Coolant Temperature (ECT) sensor
- Corroded or loose electrical connectors at the sensor
- Damaged or frayed wiring leading to the ECT sensor
- Low engine coolant level
- Thermostat stuck open or closed (less common for P1117 directly, but related)
Frequently reported on: Dodge Grand Caravan 2001-2007, Chrysler PT Cruiser 2001-2009, Jeep Liberty 2002-2007, Dodge Dakota 2000-2004, Chrysler 300M 1999-2004
Diagnostic Steps
- Locate the Engine Coolant Temperature (ECT) sensor, usually near the thermostat housing or cylinder head.
- Visually inspect the ECT sensor and its electrical connector for any signs of corrosion, damage, or loose connections.
- Ensure the engine coolant level is at the correct mark in the reservoir and radiator.
- Carefully disconnect the electrical connector from the ECT sensor. Check for bent pins or debris.
- If inspection reveals no obvious issues, consider replacing the ECT sensor. This typically involves draining a small amount of coolant, unscrewing the old sensor, and installing the new one with a new O-ring or sealant.
- Reconnect the electrical connector, refill any lost coolant, and clear the trouble code using an OBD-II scanner.
👨🔧 When to Call a Professional
If the issue persists after inspecting the wiring and replacing the Engine Coolant Temperature sensor, or if you suspect deeper electrical problems, it's best to consult a professional mechanic. Complex electrical diagnostics often require specialized tools and expertise.
Commonly Asked Questions
What does an intermittent ECT sensor signal mean?
It means the sensor is sending inconsistent or fluctuating temperature data to the car's computer, leading to confusion about the engine's actual operating temperature.
Can I drive with a P1117 code?
While you might be able to drive, it's not recommended for long. The engine's fuel delivery and ignition timing could be inaccurate, potentially leading to poor performance, increased emissions, and reduced fuel economy.
Is replacing the ECT sensor difficult?
For many vehicles, replacing the Engine Coolant Temperature sensor is a relatively straightforward DIY task, often requiring basic hand tools and about 30-60 minutes. The biggest challenge can be its location.
Does low coolant cause P1117?
Yes, low engine coolant can sometimes cause the ECT sensor to read inconsistently or out of range because it may not be fully submerged in coolant, leading to an intermittent signal.
Will clearing the P1117 code fix the problem?
Clearing the code will turn off the Check Engine Light temporarily, but it will likely return if the underlying intermittent issue with the ECT sensor or its circuit is not resolved.