I was wondering if an old (stock) engine coolant temp sensor could cause sub par fuel mileage.

I know in many fords this part is overlooked, but it's critical for proper fuel mix as it tells the ECU how hot the car is. If it's old it will tell the ECU that the engine is cooler than it should be and it dumps more fuel in - since it doesn't have the proper resistance.

I was just wondering - I have a new blue sensor ready to go in but it looks like a BITCH to do.

Thoughts?

 

Most definately. The ect sensor is not that hard to change actually just make sure to leave the coolant expansion tank cap ON or your gonna lose all your coolant when you pull the ect sensor.

 

I don't think the ECU factors in engine temp in the fuel/air ratio delivery, could be wrong though. Have you noticed a decrease in fuel efficiency since the temp sensor started acting up? If you have large hands it can be a pain but its really not that hard. You'll lose a little coolant regardless, just make sure the engine is cold before you start. 2.8 sensor DIY

 

Gotcha! I might tackle this on Saturday. I will probably remove the intake to TB plenum to get at it, plus I'm going to try and fix my cruise control.

I'm not throwing any codes, and my temp gauge never goes past 12, but I figure it's original, and since I got a blue sensor from tdiparts.com for a mere $15 I figure I might as well change it. I'm lucky to get 21-22 on the highway (on10% ethanol blend).

EDIT: I believe since it's a 4 wire sensor 2 wires are for the aux fan, 2 are for the ECU/gauge...

 

have fun with that, it took me 2 hours just to change the part.since its under soo much crap. but it will definetly help with fuel econimy., when i cahnged mine my fuel econimy nearly doubled.

 

2 questions? -

Could this be a 1.8t thing as well?

Could a faulty temp sensor cause the auxiliary fan to run more often/constant?

 

I had lots of trouble with the CTS on my old 12v. Lots of the sensors failed very quickly. I don't think that the blue sensor is the right one though. Blue is for the 1.8T. The original 2.8 sensors (both 12v and 30v) were black, and the upgraded one for the 30v is green. I could be wrong, but this is from my experience with owning different audi engines.

Also, it is a pita to get to the sensor on the 12v. There is barely any space to reach it, so I hope you have really small hands. Good luck

 

I'm fairly certain that this would apply to the 1.8 as well. It may make the fan run more often...

As for the color - I assumed since ECS had the blue one listed for my car that is is the correct one.

 

I dunno, they sent me the wrong ECT sensor once... [:@]

 

Bet you got snubbed for shipping too? ECS is such a ripoff....