Scania EMS DTC 21 Control unit

EMS Engine Management System · Scania · 2 variants

Code 21 (decimal). Some diagnostic tools show it in hexadecimal as 0015.

In short

Incorrect or unreliable data.

Variant 1

Applies to: EMS S6 IoM singlespeed (S6IM)EMS S6EMS S6 (EMS S6 EuroIII)

What does Scania EMS fault code 21 mean?

Incorrect or unreliable data.

What causes Scania DTC 21?

Internal fault in the control unit.

How does the system react?

The engine cannot be started or run as long as the fault is active.

How to fix Scania EMS fault code 21?

  1. Clear the fault code memory and turn the power off and on with the starter key.
  2. Then check if the fault code has been generated again.
  3. Renew the control unit if this is the case.

Variant 2: Fault in 2 temperature sensors in the exhaust gas aftertreatment system.

Applies to: EMS10

Detection

The engine control unit indicates that there are faults in 2 temperature sensors in the exhaust gas aftertreatment system.

Possible cause

- Fault in the temperature sensors. - Fault in the cable harness between the engine control unit and the AMS control unit. - Oil or fuel leak in the silencer, for example from injectors in the engine or in the exhaust system, V185. - Air flow through the exhaust gas aftertreatment system is too low because the exhaust system has been tampered with.

Symptoms

Regeneration of filters does not work, which leads to torque reduction being activated.

How to fix

  1. Check the other fault codes related to the temperature sensor, or fault codes regarding fuel and charge air systems.
  2. Compare the temperature sensors.
  3. Run Operational testing of exhaust gas temperature sensor.
  4. Check the injectors.
  5. Check the cable harness and harness-to-harness connectors.
  6. Check the oil level.
  7. A low oil level may indicate an oil leak.
  8. Remove the flexible bellows from the silencer.
  9. Look for fuel and oil leaks in the exhaust system between the engine and silencer.
  10. Look for black or white smoke when accelerating, which may indicate a fault in the injector or air fuel mixture.
  11. Clear white smoke may indicate hydrocarbons.
  12. Verification To verify that the fault is fixed, drive the vehicle with load for up to 60 minutes or run an Operational testing of exhaust gas temperature sensors.

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

Code 21 in other Scania systems

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