Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Engine Coolant Temperature (ECT) Sensor
On Cherokee and Wrangler, ECT sensor is installed into the thermostat housing. On Grand Cherokee, ECT sensor is mounted on top of engine, next to thermostat housing. It provides a variable signal to the PCM that is used to calculate injector pulse width and ignition timing. When engine is cold, PCM will operate engine in an open loop cycle, causing slightly higher air/fuel mixture and higher idle speeds. When normal operating temperatures are reached, PCM will operate engine in a closed loop cycle.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.