Gas gauge reads incorrectly

[RJ'sGottaDrive]

I've had my '02 C2 for a week now and have been really enjoying it.This thing can really carve turns.

It came with a full tank of gas and the gas gauge read correctly to nearly empty when I got the low fuel warning.

I filled it up, but it only took 12 gallons.

After filling, the gauge needle didn't move and the low fuel warning remained on.

The next day, the gas gauge slowly crept to almost full(about 7/8).

My initial reaction, for any car, is that it needs a new fuel gauge sending unit.

But I did read on this forum about a recalibration process that has to be done at the dealer.

Any help is always appreciated.

[JFP in PA]

1 hour ago, RJ'sGottaDrive said:

I've had my '02 C2 for a week now and have been really enjoying it.This thing can really carve turns.

It came with a full tank of gas and the gas gauge read correctly to nearly empty when I got the low fuel warning.

I filled it up, but it only took 12 gallons.

After filling, the gauge needle didn't move and the low fuel warning remained on.

The next day, the gas gauge slowly crept to almost full(about 7/8).

My initial reaction, for any car, is that it needs a new fuel gauge sending unit.

But I did read on this forum about a recalibration process that has to be done at the dealer.

Any help is always appreciated.

 

The factory recalibration.proceedure is complicated and requires a Porsche scan tool and a precise amount of fuel, but should fix your issue.

[RJ'sGottaDrive]

Thanks JFP. Any idea what Porsche will charge me for this? An hour labor?

[creekman]

I believe that Porsche of San Antonio charges $160.00/hr.  Even if you could afford the car you would be hard pressed to pay that rate.  At least I would ...  I'd hate to spend $200-$300 for the dealer to scan the system only to find out that it was the sending unit.  Depending on the cost of the sending unit I might start there...  Can anybody tell which direction is best?

[RJ'sGottaDrive]

You can buy the sending unit for $250. Looks easy to install.

Since I can do it myself, I might start there.

Would the Durametric scan tool tell me if it's the sending unit?

Might be worth buying one if it can. Good investment for the future too.

[DBJoe996]

Durametric in this case will not tell you anything.  Generally, CEL's are related to emission equipment and running conditions.  That being said, I consider Durametric a wise investment.  Now, you have had the car a week and noticed a quark with the gas gauge.  Are you really ready to spend $$$ chasing this down?  Could be the sending unit is a bit sticky from non-use. 12 gallons in would put it at about 7/8 of a full tank.  I would wait until after a few more fill ups before jumping in with $$$ to check this out. 

[JFP in PA]

12 hours ago, creekman said:

I believe that Porsche of San Antonio charges $160.00/hr.  Even if you could afford the car you would be hard pressed to pay that rate.  At least I would ...  I'd hate to spend $200-$300 for the dealer to scan the system only to find out that it was the sending unit.  Depending on the cost of the sending unit I might start there...  Can anybody tell which direction is best?

 

If memory serves , a new sending unit still requires calibration.

[RJ'sGottaDrive]

DBJoe- it's good advice and I'll do that before I spend any money. It's the anal retentive engineer in me that wants things to work correctly and right now.

 

[DBJoe996]

Running a bottle of Techron in the fuel system might help as well.  Would not hurt anything to try.  Particularly if the car has been sitting around for awhile.

[Loren]

On 7/6/2019 at 8:38 AM, JFP in PA said:

 

If memory serves , a new sending unit still requires calibration.

 

Correct.