Variant 1
Applies to: AMS1
What does Scania AMS fault code 4358 mean?
The reductant pressure is reduced too quickly when the reductant doser is opened.
What causes Scania DTC 4358?
- Blocked prefilter in reductant doser V231 or reductant doser V117. - One of the reductant dosers is overdosing reductant. - The reductant circuit elasticity is insufficient.
How to fix Scania AMS fault code 4358?
- Run the Wizard on dirt in the SCR system.
- Renew the prefilter in the reductant doser V117 and V231.
- Renew the main filter in the reductant pump.
- Check that the freeze protection is intact and that the insert in the filter housing has not been exposed to reductant, since this causes the system elasticity to decrease.
- Note: Run Exhaust gas aftertreatment, troubleshooting the liquid components of the SCR system > Metering test > Low dosage level.
- If the problems are not caused by a blockage in the reductant flow, check that the reductant hoses in the reductant circuit are Scania original.
Variant 2: The reductant doser V117, blocked prefilter
Applies to: AMS2
Detection
The pressure drops too fast when the reducer doser opens.
Possible cause
- Blocked prefilter, reductant doser V117. - The reductant doser overdoses. - Elasticity in the reductant circuit is too low.
How to fix
- Renew prefilter in reductant doser V117.
- Check that all hoses are Scania original.
- Check that the elastic membrane in the reductant pump filter housing is intact.
- Verification Run Metering test > V117 > low metering to deactivate the fault code.
This information is for guidance only. Always follow the manufacturer workshop manual and safety procedures; if in doubt, contact an authorised workshop.