Variant 1
Applies to: AMS1
What does Scania AMS fault code 4359 mean?
The reductant pressure is too high even though the reductant pump is switched off.
What causes Scania DTC 4359?
- Fault in the reductant pressure sensor or in its harness-to-harness connectors or electrical cables. - Blockage in the return hose between the reductant doser V117 and the reductant tank. - Blockage in the reductant doser.
How does the system react?
No reaction.
What are the symptoms?
A yellow warning indication is displayed. The fault results in higher exhaust emissions.
How to fix Scania AMS fault code 4359?
- Run the Wizard on dirt in the SCR system.
- Run the Exhaust gas aftertreatment, troubleshooting of the SCR system's liquid components wizard.
- If the reductant pressure sensor gives too high a value when the reductant pressure should be 0, the test will be terminated.
- Disconnect the return hose from the reductant tank.
- Check the reductant pressure by checking the reductant dosers.
- If the reductant pressure drops, the return pipe in the reductant pick-up unit may be clogged.
- If the reductant pressure remains high, disconnect the return hose for reductant doser V117.
- Disconnect the return hose carefully as the reductant pressure may be high.
- Check the reductant pressure again.
- If the reductant pressure drops there may be a blockage in the reductant doser return hose.
- If the reductant pressure remains high, check the harness-to-harness connectors and electrical cables between the EEC control unit and reductant doser V117 pressure sensor.
- If the harness-to-harness connectors and electrical cables seem to be intact, clean reductant doser V117 with water.
- If the reductant pressure remains high, renew reductant doser V117.
- When the fault is rectified, the fault code can be deactivated.
- Run the Exhaust gas aftertreatment, troubleshooting of the SCR system's liquid components wizard.
Variant 2: Reductant circuit, high pressure
Applies to: AMS2
Detection
The reductant pressure is too high when the reductant pump is shut off.
Possible cause
- Blockage on the return side of the circuit: - Outlet, reductant doser V117. - Hose between V117 and reductant pick-up unit T116. - Return pipe, reductant pick-up unit T116. - Electrical fault: - Pressure sensor in reductant doser V117.
How to fix
- Check if the reductant pressure is greater than 1 bar when reductant pump V183 is stationary.
- If this is the case, the blockage can be found by loosening the hose between V117 and the reductant pick-up unit at one of the ends.
- See whether the pressure drops.
- If the pressure drops, the blockage is downstream from the opening point.
- Warning!
- Risk of eye damage.
- Wear eye protection if the circuit is opened while pressurised.
- After blockages, check the hoses between V117 and the reductant pick-up unit, as well as the reductant pick-up unit's return pipe and the tank's venting.
- Clean the outlet on V117 with water.
- Check the cable harness between V117 and the E67 control unit.
- Renew doser V117.
- For troubleshooting purposes, consider temporarily switching to components you know are working before performing any permanent actions.
- Verification - Run Venting the SCR system to verify that the fault is fixed. - Run Pressure sensor check 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.