Signal Sporadic. Permanent Fault

Checking diagnostic trouble codes (DTCs)
- Ignition off.
- Check fuel tank pressure sensor connector for contact resistance and oxidation and remedy.
- Check control module connector for contact resistance and oxidation and remedy.
- Check connectors 24/2 and 24/4 for contact resistance and oxidation and remedy.
- Fuel tank pressure sensor connected.
- Control module connected.
- Start the engine and idle it.
- Wait 5 minutes.
- Select Volvo Scan Tool (ST) to read off diagnostic trouble codes (DTCs).

If EFI-621 is stored it should have intermittent status.

If reading is OK:
^ Proceed to Verification section below.

If reading is incorrect:
^ Proceed to next step below.























Checking cables and terminals
- Check fuel tank pressure sensor and/or control module connector for loose connections.
- Check cable between fuel tank pressure sensor terminal 3 and control module #815 for an intermittent open-circuit, intermittent short-circuit to ground and an intermittent short-circuit to supply voltage.
- Check cable between fuel tank pressure sensor terminal 2 and control module #831 for an intermittent open-circuit, an intermittent short-circuit to ground and an intermittent short-circuit to supply voltage.
- Check cable between fuel tank pressure sensor terminal 1 and control module #828 for an intermittent open-circuit.
- The fuel tank pressure sensor power cable is connected inside the engine control module (ECM) to the air conditioning (A/C) pressure sensor, atmospheric pressure sensor and accelerometer power cables. If anything happens to any of these cables all four will be affected.

Check cables between:
- air conditioning (A/C) pressure sensor terminal 3 and engine control module (ECM) #B29.
- atmospheric pressure sensor terminal 1 and engine control module (ECM) #B15.
- accelerometer terminal 1 and engine control module (ECM) #B1 for an intermittent short-circuit to supply voltage and an intermittent short-circuit to ground.
- Reinstall all components.
- Start the engine and idle it.
- Wait 5 minutes.
- Select Volvo Scan Tool (ST) to read off diagnostic trouble codes (DTCs).

If EFI-621 is stored it should have intermittent status.

If reading is OK:
^ Proceed to Verification section below.

If reading is incorrect:
^ Proceed to next step below.











Checking the air conditioning (A/C) pressure sensor
- Ignition off.
- Fuel tank pressure sensor connected.
- Disconnect air conditioning (A/C) pressure sensor.


Hint: Diagnostic trouble codes (DTCs) may be stored for the air conditioning (A/C) pressure sensor. Erase codes when fault-tracing is completed.


- Start the engine and idle it.
- Wait 5 minutes.
- Select Volvo Scan Tool (ST) to read off diagnostic trouble codes (DTCs).

If EFI-621 is stored it should have intermittent status.

If reading Is OK:
^ Proceed to next step below.

If reading is incorrect:
^ Proceed to Checking accelerometer section below.






Replacing component
Try a new air conditioning (A/C) pressure sensor.

Then continue with:
^ Verification section below.











Checking accelerometer
- Ignition off.
- Fuel tank pressure sensor connected.
- Connect air conditioning (A/C) pressure sensor.
- Disconnect accelerometer.


Hint: Diagnostic trouble codes (DTCs) may be stored for the accelerometer. Erase codes when fault-tracing is completed.


- Start the engine and idle it.
- Wait 5 minutes.
- Select Volvo Scan Tool (ST) to read off diagnostic trouble codes (DTCs).

If EFI-621 is stored it should have intermittent status.

If reading is OK:
^ Proceed to next step below.

If reading is incorrect:
^ Proceed to Checking atmospheric pressure sensor section below.






Replacing component
Try a new accelerometer.

Then continue with:
^ Proceed to Verification section below.












Checking atmospheric pressure sensor
- Ignition off.
- Fuel tank pressure sensor connected.
- Connect the accelerometer.
- Disconnect atmospheric pressure sensor.


Hint: Diagnostic trouble codes (DTCs) may be stored for the atmospheric pressure sensor; erase codes when fault-tracing is completed.


- Start the engine and idle it.
- Wait 5 minutes.
- Select Volvo Scan Tool (ST) to read off diagnostic trouble codes (DTCs).

If EFI-621 is stored it should have intermittent status.

If reading is OK:
^ Proceed to next step below.

If reading is incorrect:
^ Proceed to Replacing component section below.





Replacing component
Try a new atmospheric pressure sensor.

Then continue with:
^ Verification section below.


Replacing component
Try a new fuel tank pressure sensor. See: Fuel Tank Pressure Sensor.

Then continue with:
^ Verification section below.














Verification


Hint: After carrying out the repair, check that the fault has been remedied as follows:


- Ignition off.
- Reconnect connectors and reinstall components.
- Disconnect the Volvo Scan Tool (ST) from the VIDA station and use it in stand-alone mode.
- Test drive the car.
- Use Volvo Scan Tool (ST) to read off diagnostic trouble codes (DTCs).

If EFI-621 is stored it should have intermittent status.

If reading is OK:
^ Fault corrected

If reading is incorrect:
^ Fault not found