Scania EMD DTC 256 Intake air mass flow sensor T126

EMD EMD control unit · Scania

Code 256 (decimal). Some diagnostic tools show it in hexadecimal as 0100.

In short

The value from the mass flow sensor remains unchanged even though engine working conditions indicate otherwise.

Applies to: EMD0EMD1

What does Scania EMD fault code 256 mean?

The value from the mass flow sensor remains unchanged even though engine working conditions indicate otherwise.

What causes Scania DTC 256?

- Mass flow sensor fault. - Loose connection in the cable harness to the mass flow sensor. If the fault code has been activated many times, this is probably the cause.

How does the system react?

The engine control unit switches off the EGR circuit. The engine power is reduced. Only for vehicles with Euro 5: The fault code cannot be cleared when it is active.

How to fix Scania EMD fault code 256?

  1. Check that the mass flow sensor is properly fitted.
  2. Check that the mass flow sensor signal changes when the engine speed is increased.
  3. Check the harness-to-component connectors and cable harness of the mass flow sensor, especially if the fault code has been activated many times.
  4. Renew the mass flow sensor.
  5. Note: Always carry out a default setting of the mass flow sensor adaptation values if the mass flow sensor has been renewed, or if leakage in the engine intake system has been rectified.
  6. Verification Run the engine at idling speed and check that the mass flow sensor signal changes.
  7. Applies only to vehicles with Euro 5: If the operating time since the fault code was generated exceeds 10 hours, drain the EGR cooler as there is a risk that condensed water will form in the air-cooled EGR cooler when the EGR system has been switched off.
  8. Drain the EGR cooler according to the instructions in the Workshop Manual, subgroup 01-65.

This information is for guidance only. Always follow the manufacturer workshop manual and safety procedures; if in doubt, contact an authorised workshop.

Code 256 in other Scania systems

Compare code 256 in every system →