Anybody know any symptons caused by a faulty water thermosensor on a series 5 turbo? I'm having some strange issues with hard-starting and problems revving/driving when the car is warmed up, and I'm getting a 9 (water thermosensor) error code on the ECU, could this be the cause, anyone have issues like this before caused by it?

 

Replace it and if problem goes away, you learned to cause.

Just think, if ECU doesn't know the engine temp, how is it suppose to adjust the air/fuel ratio for the conditons.

 

yeah I'd get it fixed.. if it were carbeurated (like my race car), I wouldn't worry, but with an ECU I'd replace it.

 

It could be the plug has just come off or one of the wires is broken. There is a method of checking out the water thermo sensor in the fsm that is free at http://www.fc3s.org fuel section.

The ECU probably defaults to a rich mixture when it senses a failure of that sensor. Just a guess.

Those things are a dime a dozen at the wreck yard.

 

Yeah, I've got quite an assortment of them on parts cars that I know are working, and I checked the FSM on how to test them, haven't had a chance to go work on it yet so I was wondering what it would cause.

 

the check engine light will come on for an open or short circuit. it might also be way out of range. when the ce light is on the ecu will default to 80c, and not read the sensor. you need to check the sensor and the wiring back to the ecu.

mike

 

Yeah, I know what to check, I was more concerned with what it causes, like would it cause an extremely lean condition on cold starts, and a rich when running warm?

 

yup, the ecu thinks its never cold

mike

 

i had the same code about a week ago when i pulled the alt to get access to the sensor the connector was broken(i didnt break it) the sensor tested ok , i had to buy a injector connector at autozone fits perfect!

 

Again, I am wondering the *EFFECTS* caused by this sensor not working, I've had 5000000 reasons why it doesn't work, I want to know the effect! What does it do when it's not hooked up/functioning?

 

the computer will always think the engine is warm. so when its cold it wont richen the mixture, and when its hot it wont lean it out. it should be hard to start cold.
the 88 and older cars dont have a fail safe, if the sensor is not hooked up the ecu thinks its -32f and it will flood very very badly.

mike

 

Thanks for the info, I've got a series 5 so it sets it at 80C (175F?) Going to fix it in two hours

 

hey guys. i replaced my water thermo sensor and discovered that the wiring plug that went on the broken sensor was messed up (the wire had backed out of the plastic plug part)
so not that i replaced the sensor, i hook up the leads to the plug on the sensor and the car runs like ****... whats the deal?

 

i am having these exact same semptoms. my car floods easily, HARD AS HELL (takes me like 10 tries) to get it started in the cold. and runs rich when its hot...

when i plugged the damn new sensor in, my car runs like ****. what gives?


RAT, did you get yours replaced?