The reductant pump needs to run much slower than expected to keep the pressure during dosing.
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 pressure sensor is broken. 4. If the return flow is within limits, use the diagnostic tool to run a reductant dosing test in order to investigate if the dosing unit injector is blocked. 5. Use the diagnostic tool to investigate if the pressure sensor in the dosing unit seams to show a normal value. The pressure should close to the current ambient pressure when the reductant pump (V183) 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 expected for the actual dosing amount.
1. Blocked return hose 2. Blocked dosing unit return pipe 3. Blocked injector in the dosing unit(s) (V117, V231) 4. The reductant pressure sensor in the dosing unit (V117) gives a value that is too high