This is a review of common Code on E46 SMG pump that are due to failure of pump to provide correct system pressure.
53 (0x35) Low level of pressure reached
This error code will present itself when pressure sensor signal states system pressure is too low and does not come back within specification even when pump is energized to priming mode.
There are a number of factors that can lead to this, most common problem in order of failure.
1-Electric motor is failing, during this time motor will provide low torque and not perform fast enough to build pressure in allotted time. It will eventually lead to complete motor failure.
2-High power relay(salmon relay) is damaged. This normally is related to item (1) where the additional load is causing high current to wear out relay.
Over time the relay will become unreliable and not follow DME instructions by either staying in an ON or OFF position. this could trigger two specific codes based on bellow.
- When stuck in ON position it will cause smg pump to keep running continuously and eventually overheat and burn out SMG pump motor. (this could also Triger 54(0x36) error code to be stored)
- When stuck in OFF position it will cause smg pump to not prime to build up required pressure. (This could Triger 53 (0x35) error code to be stored)
3-Leak in hydraulic system causing loss of fluid leading to low pressure. Check for leaks. common area of smg slave cylinder or actuator leak will allow fluid level to get lower than minimum. When this happens the smg pump will starve not be able to build pressure.
4-Defective pressure sensor will cause an incorrect system pressure reading to DME and cause pump to be turned on more than needed. The actual system pressure will be higher than stated to DME but pump will be triggered to stay on longer as the feedback reading to DME will state low. (This could trigger a number of other codes 53(0x37), 53 (0x38) and 53 (0x39))
5-Wiring harness damage or fuse damage, this could occur if relay is stuck ON overheating wire harness and damaging insulation.
6-Blown Fuse power fuse will not allow power to electric motor. If fuse blown it could be related to underlying(item 1 or 2) system problem.