Help Diagnosing Fuel Temp Sensor (P0183) Problem

jimnms

Veteran Member
Joined
Jan 19, 2005
Location
Vicksburg, MS
TDI
2005 Jetta GLS Wagon 5-speed Tiptronic
A few weeks ago I was cruising down the highway I could feel a slight stutter every now and then. It felt like when in turbulence behind a truck or a gust of wind hitting the car, but I wasn't behind a truck and it wasn't windy that day. I still wasn't 100% sure if it was the car, the road, or wind, but then it started to stutter when idling, almost at times I thought the engine was going to die while idling at a traffic light.

My CEL is already on because I need to replace my glow plug harness. I checked engine codes and I had a new one, P0183, indicating the fuel temperature sensor. I got an OEM replacement part, put it in yesterday, but it didn't fix the problem.

The other posts I found mentioned the wiring or a fuse. I just went out and checked wiring and I'm not finding anything wrong. The positive isn't shorted to ground. I started the engine and I'm reading a steady 4.96v at the connector. I let it idle and warm up until it began to idle rough. When the rough idle started, I unplugged it to check the voltage again, and as soon as I unplugged it, the idle smoothed right out. It was still showing 4.96 volts.

Since it runs fine with the sensor unplugged, what could this mean? What will happen running the car with the sensor unplugged until I get this figured out? What fuse do I need to check? I'm not seeing a fuse specific for the fuel temp sensor. What else could be causing this?
 

wonneber

Top Post Dawg
Joined
Oct 12, 2011
Location
Monroe, NY, USA
TDI
2014 Jetta Sportwagen, 2014 Tiguan,2003 Jetta 261K Sold but not forgotten
It sounds to me like you pulled the coolant temp sensor off.
Was it in one of the heater hose flange?

With the car cold in the AM check with VCDS Group 007 what it says the temp is.
Shown fuel & coolant temp. They should both be close to outside air temp.

Not sure on a BEW but on an ALH motor it's inside the injector pump.

I would also want to check for continuity or lack of through it before replacing it.
 

jimnms

Veteran Member
Joined
Jan 19, 2005
Location
Vicksburg, MS
TDI
2005 Jetta GLS Wagon 5-speed Tiptronic
On the BEW, the fuel temp sensor is inline with a fuel line just to the right of the oil filter (pics on this post). It's a quick "fix." Unplug it, remove the clip, pull the sensor out, then reverse the process. In the other posts I found about this, it was mentioned wiring or a fuse could also be a problem. The ones with wiring issues, one was shorted, the other had no voltage, I'm not detecting a short and I have voltage. Another post fixed it by replacing a fuse, but didn't say which one. It doesn't seem likely to be a fuse if I'm getting voltage to the sensor, but it's still worth a try.

I also forgot to mention, during my test drive after replacing the sensor, the code didn't come back immediately even though it still ran rough. It did finally return after driving for about half an hour.

I don't have VCDS, so I can't check the sensor readings.
 

chz17

Veteran Member
Joined
May 25, 2013
Location
Boston, Mass.
TDI
2002 jetta TDI GL 5spd, 2004 jetta TDI PD
From Bentley manual wiring diagram the BEW engine G81 sensor directly wire to ECM through 60 pin connector ( pin40 is black/yellow, pin39 is lilac). It did not through the fuse.
 

jimnms

Veteran Member
Joined
Jan 19, 2005
Location
Vicksburg, MS
TDI
2005 Jetta GLS Wagon 5-speed Tiptronic
Hmm. What do I do now? It's possible I was sent a bad sensor. I can check the old sensor first to see if it was even bad before pulling the new one out. I'm not sure how to check it though. I remember one of the posts I read mentioned getting certain resistance values at certain temps.

Where should I be getting resistance though? I checked the old one last night, and I'm not getting any continuity or resistance across the two pins in the connector, or between either of the pins and the tip of the sensor at room temperature.
 

wonneber

Top Post Dawg
Joined
Oct 12, 2011
Location
Monroe, NY, USA
TDI
2014 Jetta Sportwagen, 2014 Tiguan,2003 Jetta 261K Sold but not forgotten
I would measure the resistance of both sensors first thing in the morning before starting the car.
The resistance should be close to each other.
Leave the old one in the car for the night.

After that you would have to measure the resistance at the pins mentioned above.
Wiggle the wire harness to see if it changes indicating a bad wire.
 
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