The reductant pump needs to run slower than expected to keep the pressure.
1. Use the diagnostic tool to run the reductant circuit test. 2. Disconnect the return hose at the top of the reductant tank and put it in a container. 3. With the diagnostic tool: Run the reductant return flow test. The test checks the reductant return flow. If the test fails there might be an obstruction in the return hose or in the dosing unit return pipe or the reductant pressure sensor is broken. 4. Use the diagnostic tool to investigate if the pressure sensor in the dosing unit seams to show a normal value. The pressure should be close to the current ambient pressure when the reductant pump has been turned off for several minutes. If a failure has been found and corrected, use the reductant circuit test to check that the system is working and to inactivate the fault code.
What you'll see
No driver-visible symptom recorded.
System reaction
No system-reaction text recorded.
Diagnostic depth
The control signal to the reductant pump is much lower than normal.
1. Blocked return hose 2. Blocked dosing unit return pipe 3. The reductant pressure sensor in the dosing unit (V117) gives a value that is too high