Erratic Fuel Gauge Operation and DTC P1431 - keywords cluster code gage IPC tank

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

Customer may comment that intermittently, the fuel gauge drops to empty. This may also be followed with a DTC P1431 (Fuel Level Sensor 2 Performance) present in the powertrain control module.

Note: On the 2003 Model Year vehicles, this information applies only to vehicles WITHOUT RPO FFS.

The right fuel tank profile may not be allowing the sending unit float to drop completely to lower end of travel. The system diagnostic interprets the reading as a tank that is not empty.

1. Be sure fuel tank levels are below half (preferably 1/3) full to ensure tanks will not equalize at key off.
2. Run the vehicle 20-30 minutes & watch voltages of the two sending units.
3. Record what the right side tank sending unit voltage is at its lowest value. It will likely be under 1 Volt. If voltage goes below .8, assume the jet pump, tank & sending unit are functioning properly. DTC should not set. If voltage doesn't get to .82V or below, the DTC should have set, proceed to step 4.
4. Remove sending unit, let float hang to its lowest point of travel & record voltage. When this unit is pulled, if a large amount of fuel spills out, fuel is probably not transferring properly. If transfer is OK, you would expect to see about a cup of fuel.
5. If sending unit value DOES NOT go lower than step 3, the float is hanging up on tank. If the value DOES go lower than step 3, proceed to step 6.
6. REPLACE THE RIGHT FUEL TANK (DO NOT MANIPULATE THE SENDING UNIT FLOAT ARM).

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.