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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Corvette 🢒 Engine 🢒 Engine Controls - 5.7L 🢒 DTC P1431

DTC P1431 Without FFS

Circuit Description

The right fuel level sensor measures fuel level changes within the right fuel tank.

When the fuel level is high the sensor signal voltage is high. When the fuel level is low the sensor signal voltage is low.

The powertrain control module (PCM) uses inputs from the left fuel level sensor and the right fuel level sensor in order to calculate the total fuel remaining in both fuel tanks. The PCM sends this information via class 2 to the IPC.

This diagnostic tests for a stuck right fuel level sensor signal. If the PCM determines that the fuel level (right tank) signal appears to be stuck based on a lack of signal variation expected during normal operation, this DTC sets.

The left tank fuel pump also supplies a small amount of pressurized fuel to the right fuel tank siphon jet pump through the auxiliary fuel feed rear pipe. The pressurized fuel creates a venturi action inside the siphon jet pump. The venturi action causes the fuel to be drawn out of the right fuel tank. Fuel is then transferred from the right fuel tank to the left fuel tank through the auxiliary fuel return rear pipe. The fuel system is designed to maintain a greater level in the left fuel tank then the right fuel tank when the electric fuel pump is operating. The fuel transfer rate from the left fuel tank to the right fuel tank is less than the transfer rate from the right fuel tank to the left fuel tank. Therefore, with the electric fuel pump operating, the left fuel tank level should be higher than the right fuel tank level.

The fuel level in the fuel tanks equalize when the following occur:

    • The electric fuel pump is not operating.
    • The fuel level is greater than 50 percent.

Conditions for Running the DTC

The engine is operating.

Conditions for Setting the DTC
    • The secondary fuel tank is not empty.
    • More than 241 km (150 mi) have been accumulated.
    • The PCM does not detect that the fuel level in the right fuel tank has not changed by at least 3.0 liters (0.80 gallons).

OR

    • The secondary fuel tank is not empty.
    • The primary fuel tank is not full.
    • Engine operating greater than 60 minutes.
    • The primary tank does not achieve the top of its range. Observe, after operating the engine for greater than 60 minutes the fuel in the right fuel tank will transfer to the left fuel tank.

OR

    • The secondary fuel tank is empty.
    • The primary fuel tank is full.
    • The fuel level in both fuel tanks does not change after traveling more than 284 km (200 mi). Observe, if the secondary fuel tank is empty, the primary fuel level should decrease after 284 km (200 mi).

Action Taken When the DTC Sets
    • The PCM stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
    • The vehicle fuel gage displays empty.
    • The check gages indicator illuminates.
    • The driver information center displays a message.

Conditions for Clearing the MIL or DTC
    • A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
    • A last test failed, ore current DTC, will clear when the diagnostic runs and does not fail.
    • Use a scan tool in order to clear the MIL or DTC.

Diagnostic Aids

Important: When inspecting for a deformed or 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 values are not the same, refer to Fuel Tank Replacement in Engine Controls.

Depending on the current fuel level, it may be difficult to locate a malfunctioning sending unit. The malfunction may only occur when the fuel level is full or near empty. The fuel sending unit may need to be removed for further diagnosis. A fuel level sensor that has an intermittent condition causes this DTC to set. Remove the fuel level sensor. Refer to Fuel Sender Assembly Replacement in Engine Controls in order to test the resistance of the sensor. The resistance of the sensor should change from 40 to 250 ohms. Replace the sensor if the resistance did not change or was out of range.

The following occurs with this DTC set:

    • The vehicle fuel gage displays empty.
    • The check gages indicator illuminates.
    • The driver information center displays a message.
    • The voltages in the Fuel Level Conversion Table are approximate values. Use this table to aid in diagnosis.
    • If the fuel level sensor is operating OK, test the operation of the Jet Pump.

If DTC  P0461 is also set refer to DTC P0461 .

For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

The voltage in the Fuel Level Conversion Table are approximate values. Use this table to aid in diagnosis.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step determines if a circuit condition is causing the fuel level signal to be at a fixed value.

    2.

  2. This step determines if a circuit condition is causing the fuel level signal to be at a fixed value.

    3.

  3. This step determines if fuel is being delivered to the right fuel tank jet pump.

    The fuel pump will run for 2 seconds each time it is commanded ON with the scan tool. The fuel pump must be enabled several times to achieve the time specified in the diagnostic table.

    4.

  4. This step verifies that the left fuel level sender voltage is not above the specified value. If the left fuel level sender voltage is above the specified value, the left fuel tank will have to be drained.

    5.

  5. Drain the left fuel tank until the left fuel sender voltage is within the specified range in order to keep fuel from leaking from the left fuel tank.

    6.

  6. This step determines if fuel is being transferred to the left fuel tank.

    The fuel pump runs for 2 seconds each time it is commanded ON with the scan tool. The fuel pump must be enabled several times to achieve the time specified in the diagnostic table.

    7.

  7. Foreign material in the fuel tank may cause the sensor to stick. Inspect the strainer for interfering with the float arm. A stuck sensor may not be apparent when the sensor is removed from the fuel tank. The following may have caused the DTCs to set:

    8. • The fuel tanks over filled.
    • Fuel level that is almost empty and then re-fueled with only a couple gallons.
    • The fuel level sensor un-stuck while re-fueling.
    • The fuel level sensor un-stuck on rough road or going around a corner.

  8. The PCM will not reset the mileage for this diagnostic if the fuel tanks are re-fueled to the same level as before the repair was made. Perform the following procedure in order to re-fuel the vehicle after replacing a sending unit or fuel tank.

    9. • Add 25 percent of the fuel that you removed before the repair.
    • Start and idle the engine for 5 minutes.
    • Turn OFF the engine.
    • Add the remainder of the fuel.

Step

Action

Values

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. Disconnect the right fuel level sensor electrical connector.
  2. Jumper the fuel level signal circuit to a good ground.
  3. Monitor the Enhanced EVAP Right Fuel Level Sensor voltage parameter with the scan tool.

Is the right Fuel Level sensor voltage at the specified value?

0.0 V

Go to Step 3

Go to Step 10

3

  1. Jumper the fuel level signal circuit and ground circuit together.
  2. Monitor the right Fuel Level sensor voltage parameter with the scan tool.

Is the right Fuel Level sensor voltage at the specified value?

0.0 V

Go to Step 4

Go to Step 11

4

  1. Monitor the fuel level in the left tank with the scan tool.
  2. Add fuel if the left tank is empty.
  3. Disconnect the auxiliary fuel feed rear pipe from the right fuel tank.
  4. Insert the auxiliary fuel feed rear pipe into an approved gasoline container.
  5. Command the fuel pump ON for the specified time with the PCM Output Controls on the scan tool.
  6. Measure the volume of fuel.

Is the volume of fuel greater than the specified value?

10 seconds

300 ml   (0.633 pt)

Go to Step 5

Go to Step 12

5

Observe the left fuel level sender voltage with a scan tool.

Is the left fuel level sender voltage above the specified value?

1.25 V

Go to Step 6

Go to Step 7

6

Drain the left fuel tank until the left fuel sender voltage is within the specified range. Refer to Fuel Tank Draining in Engine Controls.

Did you complete the action?

1.0-1.25 V

Go to Step 7

--

7

Important: Inspect the auxiliary fuel feed rear pipe if the right fuel tank is empty. Fuel flow to the right fuel tank is decreased during fueling if the crossover hose is collapsed or restricted.

  1. Connect the auxiliary fuel feed rear pipe to the right fuel tank.
  2. Disconnect auxiliary fuel return rear pipe from the left fuel tank.
  3. Insert the auxiliary fuel return rear pipe into an approved gasoline container.
  4. Command the fuel pump ON for the specified time with the scan tool.
  5. Measure the volume of fuel.

Is the volume of fuel greater than the specified value?

8 seconds

332.6 ml  (0.703 pt)

Go to Step 8

Go to Step 13

8

  1. Remove the right tank fuel level sensor. Refer to Fuel Sender Assembly Replacement in Engine Controls.
  2. Inspect for the following:
    3. • A stuck fuel level sensor (i.e. the fuel strainer interfering with the sensor float arm)
    • Fuel tank deformed
    • Foreign material in the fuel tank (ice)

Did you find and correct the condition?

--

Go to Step 17

Go to Step 9

9
  1. Connect the DMM between the fuel level sensor signal circuit and the fuel level sensor ground circuit (sensor side). Refer to Circuit Testing in Wiring Systems.
  2. Set the DMM to the 400ohms range.
  3. Sweep the fuel level sensor from stop to stop.

Does the resistance vary between the specified values?

40 ohms (±1 ohms) to 250 ohms (±2.4 ohms)

Go to Diagnostic Aids

Go to Step 14

10
  1. Disconnect the PCM connector C2 located on the opposite side of the manufacturer's logo. Refer to Powertrain Control Module Replacement in Engine Controls-5.7L.
  2. Test the right tank fuel level signal circuit for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 15

11
  1. Disconnect the PCM connector C1 located on the same side as the manufacturer's logo. Refer to Powertrain Control Module Replacement in Engine Controls-5.7L.
  2. Test the right tank fuel level ground circuit for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 15

12

Inspect the auxiliary fuel feed rear pipe for restrictions and repair as necessary.

Did you complete the replacement?

--

Go to Step 17

--

13

Inspect the auxiliary fuel return rear pipe for restrictions and repair as necessary.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 14

14

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

Did you complete the replacement?

--

Go to Step 17

--

15

Inspect for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 16

16

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 17

--

17

  1. Select the Diagnostic Trouble Code (DTC) option and the Clear Information option with the scan tool.
  2. Start the engine and idle at the normal operating temperature.
  3. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number with the scan tool.
  4. Operate vehicle within the Conditions for Running this DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test ran and passed?

--

Go to Step 18

Go to Step 2

18

Select the Capture Info option and the Review Info option with the scan tool.

Are any DTCs displayed that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK

DTC P1431 W/FFS

Circuit Description

The right fuel level sensor measures fuel level changes within the right fuel tank.

When the fuel level is high the sensor signal voltage is high. When the fuel level is low the sensor signal voltage is low.

The powertrain control module (PCM) uses inputs from the left fuel level sensor and the right fuel level sensor in order to calculate the total fuel remaining in both fuel tanks. The PCM sends this information via class 2 to the IPC.

This diagnostic tests for a stuck right fuel level sensor signal. If the PCM determines that the fuel level (right tank) signal appears to be stuck based on a lack of signal variation expected during normal operation, this DTC sets.

Conditions for Running the DTC

The engine is operating.

Conditions for Setting the DTC
    • The secondary fuel tank is not empty.
    • More than 241 km (150 mi) have been accumulated.
    • The PCM does not detect that the fuel level in the right fuel tank has not changed by at least 3.0 liters (0.80 gallons).

OR

    • The secondary fuel tank is not empty.
    • The primary fuel tank is not full.
    • Engine operating greater than 60 minutes.
    • The primary tank does not achieve the top of its range. Observe, after operating the engine for greater than 60 minutes the fuel in the right fuel tank will transfer to the left fuel tank.

OR

    • The secondary fuel tank is empty.
    • The primary fuel tank is full.
    • The fuel level in both fuel tanks does not change after traveling more than 284 km (200 mi). Observe, if the secondary fuel tank is empty, the primary fuel level should decrease after 284 km (200 mi).

Action Taken When the DTC Sets
    • The PCM stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
    • The vehicle fuel gage displays empty.
    • The check gages indicator illuminates.
    • The driver information center displays the LOW FUEL message.

Conditions for Clearing the MIL or DTC
    • A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
    • A last test failed, ore current DTC, will clear when the diagnostic runs and does not fail.
    • Use a scan tool in order to clear the MIL or DTC.

Diagnostic Aids

Important: When inspecting for a deformed or 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 values are not the same, refer to Fuel Tank Replacement in Engine Controls.

Depending on the current fuel level, it may be difficult to locate a malfunctioning sending unit. The malfunction may only occur when the fuel level is full or near empty. The fuel sending unit may need to be removed for further diagnosis. A fuel level sensor that has an intermittent condition causes this DTC to set. Remove the fuel level sensor. Refer to Fuel Sender Assembly Replacement in Engine Controls in order to test the resistance of the sensor. The resistance of the sensor should change from 40 to 250 ohms. Replace the sensor if the resistance did not change or was out of range.

The following occurs with this DTC set:

    • The vehicle fuel gage displays empty.
    • The check gages indicator illuminates.
    • The driver information center displays a message.
    • If the fuel level sensor is operating OK, test the operation of the Jet Pump and the transfer function.

If DTC P0461 is also set refer to DTC P0461 .

For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Step

Action

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. Connect a scan tool, record the left and right fuel level sensor voltages.
  2. Remove 5 gallons of fuel, refer to Fuel Tank Draining in Engine Controls
  3. Record the voltage on the left and right fuel level sensors.
  4. Start the engine, let the engine idle for 20 minutes.

Did the voltage increase on the left fuel level sensor after 20 minutes?

Go to Step 4

Go to Step 3

3

Transfer function is not operating properly. Refer to Fuel System Description in Engine Controls for further diagnosis.

Did you complete the repair?

Go to Step 5

--

4

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

Did you complete the replacement?

Go to Step 5

--

5

  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