Fuel Gauge Is Erratic In Below Freezing Temperatures - keywords cluster cold condensation DTC float fluctuate inaccurate inoperative intermittent IPC level P0463 sender tank water

This PI was superseded to update instructions because we are currently out of parts. Please discard PIT4280A.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

The fuel gauge is erratic and displays the incorrect fuel level in below-freezing weather.

Example concerns:

1. The fuel tank is ¾ full. While driving, the fuel gauge gradually starts to display a lower fuel level than would be attributed to regular engine fuel consumption. The fuel gauge may subsequently recover to an accurate fuel level display after driving for a period of time.
2. After being parked in below-freezing weather, the vehicle is started and the fuel gauge displays a reading of "E". After driving for a period of time, the gauge reading may slowly increase to indicate the actual fuel level present. If the ignition is then cycled, the fuel gauge may now display the actual fuel level.

Note: A P0463 Diagnostic Trouble Code may or may not be set. If it is set, the fuel gauge is commanded to "E".

The condition may be related to excess water in non-ethanol fuel at below-freezing temperatures causing ice crystals in the fuel which interfere with the proper operation of the fuel level sender.

Do not make any repairs for this concern at this time. Engineering is working on a fix for this concern.

Note: There is no GM Powertrain approved fuel additive for water removal. Methanol-containing additives are strictly prohibited due to the corrosive effect they have on fuel injectors.

Fuels containing ethanol are able to absorb excess water into solution and prevent/correct the icing issue. If low-percentage ethanol-containing fuel is available on-site (E10 or E5), it may be used as a water-absorbing fluid by adding it to the fuel tank. If the fuel tank is near full, some fuel may need to be drained off first, in order to get a sufficient concentration of ethanol to absorb the water. Until fuel level sender covers are available, advise the customer to fuel with E10, which is widely available in the U.S. Check the local gas stations for the E10 formulation.

Unfortunately, there are large portions of Canada that do not have E10 availability. There is presently no viable short-term remedy for customers in these areas - until the fuel level sender covers become available. Having these customers try a different gas station may help, as excess water can be an indication of poor underground tank maintenance at the gas station.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.