Trouble code from too good mileage?
 

So my check engine light has been on for a while now. I checked it when it first came on and found it was my exhaust manifold pressure sensor. I found out the pressure tube was plugged up with soot (common problem for my engine), but didn't have the 27mm deep well socket to take out the sensor and fix it until today.

So anyway, I took out the sensor, cleaned out the tube and then hooked up my diagnostic reader to delete the trouble code. When I did that I found out that I had 2 trouble codes, the original one for the pressure sensor and this one:

P0461 Fuel Level Sensor 1 Performance / Rationality

I watch my fuel gauge like a hawk and I know for certain that it's working just fine. While I'm not certain, the only thing I can figure is that the ECM just can't figure out how the truck could possibly go that many miles without the fuel level moving very much.

I think I should be proud of myself:D

:thumbup: :D

That's easy to fix, you just drill a small hole in the fuel tank - but put a cork in the hole while you're parked.

Don't know if your P0461 is the same as my P0461, but I get a P0461 code just about every first EOC after filling the tank. Usually the gas gauge goes to zero at the same time, and stays there until I cancel the code.

I also get a low fuel alarm (3 chimes and a message) at bump start after an EOC more than about 0.6 miles. The gas gauge will drop to zero, then back to where it belongs. It normally does this without setting a trouble code.

The fuel gauge hasn't been doing anything unusual for me. I have been doing just a tiny bit of EOC recently, but pretty much only when I'm coming to the end of my trip. I guess that could be throwing it (miles with no gallons, so to speak). Personally, I wonder wheter it might be the fact that I generally run the tank down fairly low before filling up (replying more on the in-cab display for miles to empty, than the fuel gauge itself). This last time I stretched it a little more than I normally do the last few times. The gauge itself was on E for quite a few miles. That might have thrown it--again, lots of miles with no detectable gallons (according to the fuel gauge).

I'm not really concerned or anything--just amused.

The idea as to why is funny, no question. After a weekend of wrenching on the XJ -- with different codes coming up -- I'll also hope things are as you say they are.