This article addresses the common E46 SMG pump Code 53 (0x35) typically resulting from the pump’s inability to generate the correct system pressure.
The error code 53 (0x35), indicating a low-pressure level, typically appears when the pressure sensor signal shows that the system pressure is insufficient, and it fails to return to the normal range even when the pump is activated to the priming mode.
Several issues may cause this error, listed here by the likelihood of occurrence:
1- The electric motor is failing: During this period, the motor will produce low torque and will not generate pressure quickly enough. This will eventually lead to total motor failure.
2- The high power relay (salmon relay) is damaged: This issue often relates to the first one as the extra load results in high current that wears out the relay. Over time, the relay becomes unreliable and fails to follow DME instructions, staying either ON or OFF. This situation could result in two specific codes based on the relay position. If the relay is stuck in the ON position, it will cause the SMG pump to overheat and burn out the SMG pump motor, possibly triggering a 54(0x36) error code. If stuck in the OFF position, the SMG pump will not prime to build up the necessary pressure, possibly triggering a 53 (0x35) error code.
3- A leak in the hydraulic system: This problem can lead to fluid loss and low pressure. Check for leaks. Common areas of SMG slave cylinder or actuator leaks could lower fluid levels. If so, the SMG pump will not generate pressure.
4- A defective pressure sensor: This could lead to an incorrect system pressure reading to DME, causing the pump to be triggered more often than required.
5- Wiring harness or fuse damage: This could occur if the relay is stuck in the ON position, overheating the wire harness and damaging insulation.
6- A blown power fuse: This can prevent power supply to the electric motor. If the fuse is blown, it could indicate an underlying system issue (item 1 or 2).
