GM Service Manual Online
For 1990-2009 cars only

DTC P0462 Without FFS

Circuit Description

The left fuel level sensor measures fuel level changes within the left fuel tank and changes resistance based on fuel level. The PCMmonitors changes in the resistance of the sensor to determine fuel level.

When the fuel tank is full, the sensor resistance is high, and the PCM senses high signal voltage. When the fuel tank is empty, the sensor resistance is low, and the PCM senses a low signal voltage.

The PCM uses inputs from the fuel level sensor to calculate the total fuel remaining in the fuel tanks. This information is then sent to the IPC via the class 2 serial data circuit.

When the PCM senses a signal voltage lower than the normal operating range of the sensor, this DTC sets.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

    • Fuel level sensor voltage for the left fuel level sensor is below 0.39 volts.
    • The fuel level signal is less than 3.5 percent.
    • The above conditions are present for greater than 2 minutes.

Action Taken When the DTC Sets

    • The DIC displays the LOW FUEL message.
    • The fuel gage defaults to empty.
    • The check gages indicator illuminates.
    • The PCM records the operating conditions at the time the diagnostic fails. The PCM displays the failure information in the Failure Records on the scan tool.

Conditions for Clearing the DTC

    • The DTC becomes history when the conditions for setting the DTC are no longer present.
    • The history DTC clears after 40 malfunction free warm-up cycles.
    • The PCM receives the clear code command from the scan tool.

Diagnostic Aids

Important: When inspecting for a deformed or a warped fuel tank, measure the resistance of the suspect fuel level sensor at empty, with the sensor in the fuel tank, and again with the sensor removed from the fuel tank. The measured resistance values should be the same at empty. If the measured resistance values arenot the same, refer to Fuel Tank Replacement in Engine Controls.

    • Use the Freeze Frame and/or Failure Records data in order to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data may aid in determining the number of miles since the DTC set.
    • The Fail Counter and Pass Counter can also aid in determining the number of ignition cycles that the diagnostic reported a pass and/or fail. Operate the vehicle within the same freeze frame conditions (RPM,engine load, vehicle speed, temperature, etc.). This will isolate when theDTCfailed.
        Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Tests for the proper operation of the circuit in the high voltage range.

Step

Action

Value(s)

Yes

No

Schematic Reference: Instrument Cluster Schematics

1

Did you perform the IPC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2

  1. Install a scan tool.
  2. Turn the ignition ON , with the engine OFF.
  3. With a scan tool, observe the Fuel Tank Level Remaining parameter in the PCM Enhanced EVAP data list.

Does the scan tool indicate that the Fuel Level parameter is less than the specified value?

4%

Go to Step 3

Go to Diagnostic Aids

3

  1. Turn the ignition OFF.
  2. Disconnect C408.
  3. Turn the ignition ON, with the engine OFF.
  4. With a scan tool, observe the Fuel Level parameter.

Does the scan tool indicate that the Fuel Tank Level Remaining parameter is greater than the specified value?

98%

Go to Step 5

Go to Step 4

4

Test the signal circuit of the fuel level sender for a short to ground. Refer to Circuit Testing and to Wiring Repairs in WiringSystems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 7

5

Test the signal circuit of the fuel level sensor for a short to ground between C408and the fuellevelsensor.Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 6

6

Inspect for poor connections at the harness connector of the fuel level sensor. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 8

7

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

8

Replace the fuel level sensor. Refer to Fuel Sender Assembly Replacement in Engine Controls.

Did you complete the replacement?

--

Go to Step 10

--

9

Important: Program the replacement PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls.

Did you complete the replacement?

--

Go to Step 10

--

10

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC.

Does the DTC reset?

--

Go to Step 2

System OK

DTC P0462 W/ FFS

Circuit Description

The left fuel level sensor measures fuel level changes within the left fuel tank and changes resistance based on fuel level. The powertrain control module (PCM) monitors changes in the resistance of the sensor to determine fuel level.

When the fuel tank is full, the sensor resistance is high, and the PCM senses high signal voltage. When the fuel tank is empty, the sensor resistance is low, and the PCM senses a low signal voltage.

The PCM uses inputs from the fuel level sensor to calculate the total fuel remaining in the fuel tanks. This information is then sent to the instrument panel cluster (IPC) via the class 2 serial data circuit.

When the PCM senses a signal voltage lower than the normal operating range of the sensor, this DTC sets.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

    • Fuel level sensor voltage for the left fuel level sensor is below 0.39 volts.
    • The fuel level signal is less than 3.5 percent.
    • The above conditions are present for greater than 2 minutes.

Action Taken When the DTC Sets

    • The driver information center (DIC) displays the LOW FUEL message.
    • The fuel gage defaults to empty.
    • The check gages indicator illuminates.
    • The PCM records the operating conditions at the time the diagnostic fails. The PCM displays the failure information in the Failure Records on the scan tool.

Conditions for Clearing the DTC

    • The DTC becomes history when the conditions for setting the DTC are no longer present.
    • The history DTC clears after 40 malfunction free warm-up cycles.
    • The PCM receives the clear code command from the scan tool.

Diagnostic Aids

Important: When inspecting for a deformed or a warped fuel tank, measure the resistance of the suspect fuel level sensor at empty, with the sensor in the fuel tank, and again with the sensor removed from the fuel tank. The measured resistance values should be the same at empty. If the measured resistance values are not the same, refer to Fuel Tank Replacement in Engine Controls.

    • Use the Freeze Frame and/or Failure Records data in order to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data may aid in determining the number of miles since the DTC set.
    • The Fail Counter and Pass Counter can also aid in determining the number of ignition cycles that the diagnostic reported a pass and/or fail. Operate the vehicle within the same freeze frame conditions (RPM, engine load, vehicle speed, temperature, etc.). This will isolate when the DTC failed.
        Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The number below refers to the step number on the diagnostic table.

  1. Tests for the proper operation of the circuit in the high voltage range.

Step

Action

Value(s)

Yes

No

Schematic Reference: Instrument Cluster Schematics

1

Did you perform the IPC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2

  1. Install a scan tool.
  2. Turn the ignition ON , with the engine OFF.
  3. With a scan tool, observe the Fuel Tank Level Remaining parameter in the PCM Enhanced EVAP data list.

Does the scan tool indicate that the Fuel Level parameter is less than the specified value?

4%

Go to Step 3

Go to Diagnostic Aids

3

  1. Turn the ignition OFF.
  2. Disconnect C402.
  3. Turn the ignition ON, with the engine OFF.
  4. With a scan tool, observe the Fuel Level parameter.

Does the scan tool indicate that the Fuel Tank Level Remaining parameter is greater than the specified value?

98%

Go to Step 5

Go to Step 4

4

Test the signal circuit of the fuel level sender for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 7

5

Test the signal circuit of the fuel level sensor for a short to ground between C402 and the fuel level sensor. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 6

6

Inspect for poor connections at the harness connector of the fuel level sensor. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 8

7

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

8

Replace the fuel level sensor. Refer to Fuel Sender Assembly Replacement in Engine Controls.

Did you complete the replacement?

--

Go to Step 10

--

9

Important: Program the replacement PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls.

Did you complete the replacement?

--

Go to Step 10

--

10

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC.

Does the DTC reset?

--

Go to Step 2

System OK