Fault code: EMS 42255 SCANIA

Error identification:

The pressure in the SCR system is implausible in comparison with the atmospheric pressure.

Cause:

The fault may be due to:

• The atmospheric pressure sensor is defective.

• A blockage in the return hose between the main unit and the reductant tank or in the bleed hose for the reductant tank.

• Fault on main unit.

• Fault on the main unit pressure sensor.

• Fault on the ventilating valve.

• The diaphragm pump has been damaged by diesel.

Notes:

The fault causes reductant injection to be switched off.

Action:

Check whether there are fault codes in the coordinator which indicate faults on the atmospheric pressure sensor.

Check that there is no blockage in the return pipe between the main unit and the reductant tank.

Check that there is no blockage in the bleed pipe for the reductant tank.

Check the cable harness.

If everything else is OK, as a last resort renew the main unit.

In order for the control unit to verify that the fault has been rectified, it must carry out a test sequence. When the control unit has carried out the entire test sequence without detecting a fault, the fault becomes inactive.

The conditions under which the control unit carries out the test are:

• There must not be any other fault codes relating to faults on the main unit.

• The SCR system must have carried out a complete system shutdown. It takes approximately 90 seconds after the starter key has been switched off for the SCR system to switch off.

The control unit must carry out the test in four successive cycles. Start the engine and run it at idling speed for at least 3 minutes. Then turn the power off and on four times, at intervals of at least 90 seconds.

You can enter under fault code monitoring and look at the fault code. There you can see whether the conditions under which the control unit verifies that the fault is rectified have been met. When the conditions are met and the test is run, the status of the fault code during the test is displayed. If the fault code is pending, the control unit has detected a fault. If the fault is resolved, the fault code becomes inactive. Clear the fault code.

Switch the power off and on with the starter key three times in succession at 10 second intervals to extinguish the warning lamp.