Fuel Temperature Sensor

Swanji · Post by **Swanji** » Wed Jun 07, 2023 3:19 pm

2002 Pathfinder SE

I replaced my fuel pump, and that works fine, but when I started the car I got a P0181 and P0183. Those deal with the fuel temperature sensor. I know there's a fuel temp sensor in the tank attached to the fuel sender. I measured the resistance of that one, and at 92 degrees F the resistance is 1,600 ohms. According to everything I can find online, that is within acceptable range.

I have continuity from the wiring to ground. So it's not a wiring issue.

Is there another fuel temperature sensor in the engine bay, perhaps, that could be the cause of the problem? I can't find one mentioned on Google.

I appreciate any suggestions anyone can offer!

Post by **VStar650CL** » Wed Jun 07, 2023 7:51 pm

Will they erase? If you cycled the key while the fuel pump was out or disconnected, those are usually the codes you'll get. Like a lot of emissions codes, FTT codes usually read "current" until they're erased or an SRT is passed, even if the underlying condition is already fixed.

Swanji · Post by **Swanji** » Wed Jun 07, 2023 8:31 pm

VStar650CL wrote: ↑
Wed Jun 07, 2023 7:51 pm
Will they erase? If you cycled the key while the fuel pump was out or disconnected, those are usually the codes you'll get. Like a lot of emissions codes, FTT codes usually read "current" until they're erased or an SRT is passed, even if the underlying condition is already fixed.

Yeah, they'll erase. And then they pop back up again as current, unfortunately.

Post by **VStar650CL** » Thu Jun 08, 2023 5:38 am

P0183 means an open signal or ground connection, you'd be getting P0182 if anything was shorted. It's a pretty simple-minded circuit, there's a fixed-value pullup resistor inside the ECM and the FTT acts as a variable pulldown that changes with temperature. So what comes out in between them is a divided voltage depending on the FTT's resistance. Measure across the terminals at the FTT and from each wire to the chassis. If there's no voltage across the wires then one of them is open. If Green/Black to the chassis reads 0V then the open is in the signal wire between the ECM and the sensor. If it reads 5V but the black wire also reads 5V with the sensor connected, then the open is in the ground wire. See EC-303 here for the wiring diagram:
https://www.nicoclub.com/service-manual ... 2%2Fec.pdf

Swanji · Post by **Swanji** » Thu Jun 08, 2023 6:45 am

VStar650CL wrote: ↑
Thu Jun 08, 2023 5:38 am
P0183 means an open signal or ground connection, you'd be getting P0182 if anything was shorted. It's a pretty simple-minded circuit, there's a fixed-value pullup resistor inside the ECM and the FTT acts as a variable pulldown that changes with temperature. So what comes out in between them is a divided voltage depending on the FTT's resistance. Measure across the terminals at the FTT and from each wire to the chassis. If there's no voltage across the wires then one of them is open. If Green/Black to the chassis reads 0V then the open is in the signal wire between the ECM and the sensor. If it reads 5V but the black wire also reads 5V with the sensor connected, then the open is in the ground wire. See EC-303 here for the wiring diagram:
https://www.nicoclub.com/service-manual ... 2%2Fec.pdf

Thank you, I appreciate it. I'll try that out

Swanji · Post by **Swanji** » Wed Jun 14, 2023 9:29 am

Update:
As I get older, my memory gets more faulty. The code I was actually getting was P0182, which as mentioned above is a short, not an open.

I removed the sender from the tank, and found the temp sensor had detached from the metal rod it was mounted to, and was dangling. Apparently the contacts on the end of the dangling sensor had been trapped against something metal, probably the rod, and therefore developed a short. I re-mounted the sensor onto the rod and put everything back together. Measured resistance across the pins on the top of the sender. Resistance looked good. I've driven about 50 miles since then, and no codes have returned. Job done.0

Thanks for the assistance.

Post by **VStar650CL** » Wed Jun 14, 2023 9:36 am

Fuel Temperature Sensor

Fuel Temperature Sensor

Re: Fuel Temperature Sensor

Re: Fuel Temperature Sensor

Re: Fuel Temperature Sensor

Re: Fuel Temperature Sensor

Re: Fuel Temperature Sensor

Re: Fuel Temperature Sensor

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