Fault code: 43521 SCANIA

Error identification:

The measured level of nitrogen oxides (NOx) is higher than it should be.

Cause:

The SCR system does not reduce the nitrogen oxides correctly.

Notes:

Action:

1. Check that there are no other active fault codes that are related to emission levels.

2. Check that the reductant in the reductant tank is of an approved quality.

3. Check that neither the reductant lines nor injection nozzle are blocked. Crystals can be rinsed out with water.

4. Check that the reductant doser is not blocked. Crystals can be rinsed out with water.

5. Check that the catalytic converter is not damaged.

6. Check that the catalytic converter substrate material is not damaged.

Verification

There are two alternatives:

• Run Verifying rectified fault codes for NOx monitoring. The test should be carried out outdoors because the exhaust gases become very hot and there is a risk that the vehicle exhaust extraction system will be damaged. The test takes approximately 5-30 minutes to carry out, depending on which fault codes are active.

• Road test the vehicle with a heavy load, 4 times in succession with the engine switched off in between.