996 Gas Gauge Shows Allways Full

[porschester]

Hello Everyone...This is my first post...and I am happy to be a new member....

Several weeks ago, the gas gauge on my 996 carrera kept showing full, since this is my secondary car, I ended up running out of gas twice with a needle showing full. The Collection Dearlership said initially that they could not figure out the problem (!!!!) Now the Service/Sales guy is telling me that he needs to run diagnostics for 4 hours at the cost of $120 an hour just to found out what is causing the gauge needle to stay up....and then charging more for the actual fixing. My car has only 15K miles. I am not having good vibes about what is happening, and I am quite perplex about the service guy making this issue look as if it is complex and expensive....could anyone share some feedback or any recommendations?? Should't this be fairly easy for "The collection" dealer in Miami to service without implicating long hours of diagnostics and labor?? Thank You in advance for your shared thaughts and comments.

Sincerely

Porschester

[Loren]

Your car is a MY01 C4 right?

Chances are it is time to find a new dealer... There is a TSB on this. (TSB 9/99 2015 Carrera 4 – Running Out of Fuel -- dated 10-4 -1999)

In all current models except the 911 Carrera 4 (996), the fuel level warning light (reserve) illuminates when there is approx. 10 liters of fuel remaining in the fuel tank. When the reserve light comes on, the driving-distance-on-remaining-fuel (trip computer) is calculated by monitoring the fuel consumption signal (ti), and continues until the fuel tank is empty (or refilled).

In the case of the 911 Carrera 4 (996), the shape and configuration of the fuel tank prevent the fuel level sensing system from being able to physically read down to a level of 10 liters. Therefore, on the 911 Carrera 4 the driving-distance-on-remaining-fuel calculation begins when the fuel reaches a level of 19 liters (approx. 1/4 tank).

As fuel is further consumed below 19 liters, the amount of fuel remaining in the tank is a calculated value. The calculated value is derived from the fuel consumption signal (ti), and continues until the fuel tank is empty (unless the fuel tank is refilled).

Whenever the fuel level is less than 19 liters and the ignition is switched off, the fuel-level and driving-distance-on-remaining-fuel values are stored in instrument cluster memory.

If battery power is interrupted, these stored values are lost (erased from instrument cluster memory). Once lost, these values will not be automatically recalculated unless the fuel tank is filled with at least 19 liters (crossing the calculation-switchover threshold).

To summarize, if the battery is disconnected with the fuel level less than 1/4 tank, the fuel level and driving-range-on-remaining-fuel values will be incorrect. When the battery is reconnected, the fuel calculation will default to 19 liters, when in fact, the fuel level is most likely less than 19 liters. This can result in the vehicle running out of fuel, with a seemingly good fuel level indication.

If the battery must be disconnected on a 911 Carrera 4 (996), perform one of the following to prevent running out of fuel:

1. Fill the fuel tank with more than 19 liters of fuel (1/4 or more) before disconnecting the battery. This will eliminate the danger of invalid values being stored because the fuel level will already be above the calculation switching point when the battery is reconnected.

or

2. Fill the fuel tank with at least 19 liters of fuel after reconnecting the battery. This will reset the calculation process with valid values.

If it is not this problem then you either need a new sending unit or instrument cluster - a 5 minute test with a PST2 (or PIWIS) tester should determine that. My money is on the TSB problem.

[porschester]

Dear Loren....You have been a member of PCA since 1978...so I put my money on your recommendation. Thank You very much for your advice. I will print this note and take it to service first thing on Monday...I will keep you posted on his next song....Once again Loren Thank You for your input...Cheers

Your car is a MY01 C4 right? YES

Chances are it is time to find a new dealer... There is a TSB on this. (TSB 9/99 2015 Carrera 4 – Running Out of Fuel -- dated 10-4 -1999)

If it is not this problem then you either need a new sending unit or instrument cluster - a 5 minute test with a PST2 (or PIWIS) tester should determine that. My money is on the TSB problem.

[Izzy]

You said it all, The Collection in Miama, run away....... I am surprised they didn't ask for 8 hours of testing. Go up to Broward and get a second opinion

[hsummy]

Dear Loren....You have been a member of PCA since 1978...so I put my money on your recommendation. Thank You very much for your advice. I will print this note and take it to service first thing on Monday...I will keep you posted on his next song....Once again Loren Thank You for your input...Cheers

Your car is a MY01 C4 right? YES

Chances are it is time to find a new dealer... There is a TSB on this. (TSB 9/99 2015 Carrera 4 – Running Out of Fuel -- dated 10-4 -1999)

If it is not this problem then you either need a new sending unit or instrument cluster - a 5 minute test with a PST2 (or PIWIS) tester should determine that. My money is on the TSB problem.

Just to give you more piece of mind, I experienced the exact same problem on my C2 02 cab, the dealer replaced the sending unit first, this did not fix the problem, the dealer then replaced the instrument cluster, still did not solve the problem, the dealer tested the sending unit and ended up replacing the instrument cluster again, finally solving the problem. Seams like the clusters can be problematic. The dealer did all my work under warranty.