Jaguar - fault code?

[57jam89]

Hi all,
I have a jag s type which after a while driving on gas throws up fault code P0460 which is - Fuel level sensor circuit
range/performance, Fuel level sensor to rear electronic control module circuit(s), intermittent short circuit, open circuit, high resistance or Fuel level sensor failure.

I'm thinking the ecu thinks 'fuel level sensor failure' due to knowing it's injecting fuel but can't see petrol level dropping.

What do you think?

[Gilbertd]

Certainly looks that way. It isn't like it's saying it's short circuit, it's saying it might be short circuit, or open circuit, or high resistance or it's died. It's detecting that something isn't right but doesn't know what. As you say, the engine is running, fuel is being used but the level isn't going down so it must be a fault with the level sensor. Damn modern cars, they think too much.......

[Tubbs]

What's the crack with the fuel return on this install ?

[LPGC]

What's the crack with the fuel return on this install ?

Yeah I can see where Tubbs is coming from... A few hours ago I was running a petrol pipe back to the tank (fuel return) on an L322 with Jag V8.

Few potentials including - A dodgy potentiometer on the fuel gauge sender / LPG installer trying but failing to install a petrol gauge fix (prevent gauge dropping when running on LPG) / An amateur confusing the fuel pressure sensor with fuel level sender (wiring in a pressure sender fix to fuel gauge).

Not a fault code often seen.

Simon

[Martec]

Can I just add a little to this post, I have a MY2000 3ltr maual S type Jaguar which still runs on petrol.

The fuel tank is effectively a saddle tank, it goes up and over the propshaft so at low levels there is effectively two tanks. The drivers side of the tank contains the fuel pump and its own small fuel chamber. The fuel is pumped to an eductor in the passenger side of the tank and on to the engine, this lifts the fuel from the passenger side back to the driverside chamber to permanently feed the pump.

I assume one of the ECU's (ours is a 'standard' car so only has 11 ecu's) receives the signal from both level sensors and calculates a common level for the fuel gauge.

I have often wondered if on LPG and the fuel supply to the engine shut off, is the pump still running to educt fuel back to the drivers side? Would this give some odd fault codes?

Brian

[57jam89]

What's the crack with the fuel return on this install ?

Hi Tubbs, don't you remember! You adjusted my fuel trims. The car reg is E7 LPG.

And yes petrol return fitted.

[57jam89]

Can I just add a little to this post, I have a MY2000 3ltr maual S type Jaguar which still runs on petrol.

The fuel tank is effectively a saddle tank, it goes up and over the propshaft so at low levels there is effectively two tanks. The drivers side of the tank contains the fuel pump and its own small fuel chamber. The fuel is pumped to an eductor in the passenger side of the tank and on to the engine, this lifts the fuel from the passenger side back to the driverside chamber to permanently feed the pump.

I assume one of the ECU's (ours is a 'standard' car so only has 11 ecu's) receives the signal from both level sensors and calculates a common level for the fuel gauge.

I have often wondered if on LPG and the fuel supply to the engine shut off, is the pump still running to educt fuel back to the drivers side? Would this give some odd fault codes?

Brian

On s types 2002 onwards can't have petrol shut off/not being used as it upsets the high pressure fuel rail sensor. They have to have a fuel return to the petrol tank which opens the moment it switches to lpg. So then running on gas the petrol pump is still pumping fuel to the fuel rail and the returning to tank.

I think some earlier s type like yours don't need this.

[LPGC]

On s types 2002 onwards can't have petrol shut off/not being used as it upsets the high pressure fuel rail sensor. They have to have a fuel return to the petrol tank which opens the moment it switches to lpg. So then running on gas the petrol pump is still pumping fuel to the fuel rail and the returning to tank.

I think some earlier s type like yours don't need this.

Agreed for the most part, but instead of a physical fuel return some installers fit an electronic fuel pressure emulator (which seldom work long term). If one of these is fitted, it is possible the fuel pump is disconnected but still very highly unlikely.

The OP's OBD error is uncommon but there are mentions on Jag forums concerning petrol only cars with this error, seems usually due to a problem with the level gauge - just like the code description spells out.

Vague on this but I think I have seen latent codes for this error (on Jags) that never develop to full codes. A reasonable expectation too, because if the ECU believes vehicle is running on petrol but FLI fuel level input never decreases, after a few hundred miles say, then on a petrol only vehicle there would definitely be something amiss with the FLI.

Simon

[57jam89]

Vague on this but I think I have seen latent codes for this error (on Jags) that never develop to full codes. A reasonable expectation too, because if the ECU believes vehicle is running on petrol but FLI fuel level input never decreases, after a few hundred miles say, then on a petrol only vehicle there would definitely be something amiss with the FLI.

Simon[/quote]


Hi Simon, Yes I thing your spot on! If I switch back to petrol the fault clears itself and the 'fuel range' on the dash starts to work again but if I turn lpg back on then about 4/5 weeks later (after about 2000 miles) the 'fuel range' stops working followed by fault code PO460.

This does not worry me, just posting details to maybe help others out.

Damn modern cars, they think too much.......

[Tubbs]

Yes ! I do remember. It was blue ? Lol.

[57jam89]

Yes ! I do remember. It was blue ? Lol.

What's the one!