Engine coolant temperature is lower than thermostat
My Service Engine Soon light came on, I went to AutoZone and had their reader hooked up to my car and it said my engine coolant temperature is lower than the thermostat. What does that mean? It also said that my Bank 1 Sensor 2 oxygen sensor was bad. I replaced it. Are these 2 problems related? My car seems to be running fine now that i've changed the sensor, but the service engine soon light is still on.
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P0119CadillacEngine Coolant Temperature Circuit Intermittent
- Low engine coolant level
- Faulty Engine Coolant Temperature (ECT) sensor
- Faulty engine coolant thermostat
- Engine Coolant Temperature (ECT) sensor harness is open or shorted
- Engine Coolant Temperature (ECT) sensor electrical circuit poor connection
What about the obd code?
The Engine Control Module (ECM) detected an erratic signal from the engine Coolant Temperature (ECT) sensor during the system monitor test
- Engine Light ON (or Service Engine Soon Warning Light)
P0119 Cadillac Description
The Engine Coolant Temperature (ECT) sensor is used to detect the engine coolant temperature. The sensor modifies a voltage signal from the Engine Control Module (ECM). The modified signal returns to the ECM as the engine coolant temperature input. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.
P119 or P0119 ?
code p0128 refers to coolant thermostat--coolant below thermostat regulating temperature==causes mechanical fault. ( thermostat stuck open --replace it) If you are experiencing cold weather then there is a problem with the ecm settings as the ecm should be compensating for the cold ambient temperature and setting the fuel mixture to richer than normal ( same as using a choke). Check the fault codes again and check for a coolant sensor fault.
code P0128 :say that the engine is not running normal temp.but less.how the pcm can say that . it's receiving info from coolant sensor. 2things one the coolant sensor is telling the right temp. or the thermostat don't. Change thermostat and see if it change the condition.
The service engine soon light is a tell tale light that reports to the driver if there are sensor problems with the engine. It looks at coolant temperature, Throttle position, altitude, outside air temperature, fuel mixture and other things to make your car run good and smooth with many years of reliability.
Could be the thermostat. I know nothing about cars but I noticed my 2000 Grand Prix temp gauge was not going to the normal level. My wife drives this car so I didn't notice it for a month or so. Eventually the Engine light came on. Took it to Autozone and the code came back as P0180... (1) low coolant (2) bad thermostat (3) enginge fuel temp sensor. They used a code reader that was about the size of an Ipod nano.
Coolant was okay, so took it to my mechanic. His netbook sized computer showed it was the Thermostat. He reset the codes and the temp guage went back to normal. Was short on $40 for the fix at the time, so I parked the car and promised to bring it back in 3 days. Went out and checked the car a day later at 25 degrees outside without starting the car... gauge still sitting at the normal level. No question it's the thermostat. That car will not be driven again until T.stat is fixed in 2 days.
Buy a scanner or go to Autozone and have them pull the codes out. get back to me with the codes and I'll figure it out for you.
But the fan could be the relay or the coolant temperature sensor and ECU that controls the circuit. Have the coolant , hoses and thermostat been changed lately. Start with those things.
Get the shop manual and test the coolant temperature sensor,relay and ECU. These are simple checks usually a visual inspectionor a little probing with a Digital Voltmeter will solve the problem.