I've been getting this lately. I know what it is, but I also am trying to answer a couple questions along the way. And here are my various scenarios I've worked through:
1. ECL comes on, run JSCAN and get P0128 code.
2. Clear code.
3. Cold start JK, ECL immediately comes on. Question #1- how is this code thrown when the engine is cold? Whether or not I clear the code is irrelevant, it will immediately show when I start hot or cold.
1. ECL comes on, run JSCAN and get P0128 code.
2. Top off coolant (maybe 1" below hot line), clear code.
3. 1-2 days later, ECL comes on; (you guessed it- same code).
4. ECL immediately throws code upon starting, hot or cold.
1. When ECL came on, as expected, this morning, I ran JSCAN all the way to work on the back roads- 45mph with a few stoplights along the way. Coolant temp never went higher than 187 and was 73 when I started the engine (air temp this morning was 60).
At this point, although I'm not real concerned that my engine is running cooler than it should, I'll order a new OEM sensor and likely a new thermostat as well. I'll start with the new sensor for a few days and then pop in the new thermostat if that doesn't solve anything.
1. ECL comes on, run JSCAN and get P0128 code.
2. Clear code.
3. Cold start JK, ECL immediately comes on. Question #1- how is this code thrown when the engine is cold? Whether or not I clear the code is irrelevant, it will immediately show when I start hot or cold.
1. ECL comes on, run JSCAN and get P0128 code.
2. Top off coolant (maybe 1" below hot line), clear code.
3. 1-2 days later, ECL comes on; (you guessed it- same code).
4. ECL immediately throws code upon starting, hot or cold.
1. When ECL came on, as expected, this morning, I ran JSCAN all the way to work on the back roads- 45mph with a few stoplights along the way. Coolant temp never went higher than 187 and was 73 when I started the engine (air temp this morning was 60).
At this point, although I'm not real concerned that my engine is running cooler than it should, I'll order a new OEM sensor and likely a new thermostat as well. I'll start with the new sensor for a few days and then pop in the new thermostat if that doesn't solve anything.