SMG 2 is the “sequential” transmission option for the E46 M3, introduced for the 2002 model year. It utilizes the same Getrag 420G transmission as the traditional manual car but with electrohydraulic actuation of the shift linkage and clutch. It is driven similarly to the M-DCT’s in newer M cars.

General Information:

Soft Reset:

SMG works by “learning” your driving style and adjusting to it. Sometimes this will lead to slurry clutch engagement. You can do a soft reset on the SMG by putting the car in neutral above 45mph and holding the + and – paddle at the same time for 5 seconds to reset what the transmission has learned.

Fluid Type:

Pentosin CHF-11S

Checking SMG hydraulic fluid level:

The fluid level for the SMG needs to be checked while the pump is pressurized. To check, take the cap off of the reservoir (located on top of the airbox) and set it aside. Turn the ignition to on and you should hear the SMG pump prime. Quickly check the level in the reservoir using the dipstick built into the cap before the pressure has a chance to drop.

Bleeding actuator/clutch:

Click here for a guide on bleeding the SMG hydraulics.

Common failures:

SMG Pump Motor (Most Common):

When the pump motor fails it will often fail to reach the targeted hydraulic pressure and cause the yellow gear cog warning light to illuminate. If the motor begins to overheat the car will pop into neutral and not go back into gear until it cools down.

SMG Pump Accumulator:

Accumulator failures can cause your car to have a delay between turning the key and the starter motor engaging. This is due to the pump needing extra time to build up pressure to put the car in neutral and start. Accumulators that have totally failed will cause the pump motor to run constantly and eventually burn out.

Hood Latch Sensors:

These can cause issues if they fail and make the car think the hood is open. You can check their status in INPA to see if they have gone bad.

Salmon Relay/40A Fuse:

These were blamed for SMG failure symptoms in the past. While it is possible that a bad relay could cause a pump motor to act up it is fairly unlikely. However, both are cheap and easily replaced. The part number for the relay is 12631742690. The 40a fuse part number is 61138367132.

Gear Position Sensor:

The gear position sensor failing can cause sluggish shifts in SMG and in extreme cases make the car start skipping gears entirely. The gear indicator may flash while the car tries to find the gear.

Compression Springs:

Compression springs can cause similar symptoms to a faulty gear position sensor. It is advised to replace the compression springs any time the transmission is off of the car, as the springs are very cheap and easy to do with the transmission out.

CSL SMG Flash and slurry clutch engagement:

I fixed this on my car by flashing my DME with the inertia update. Click here for the DIY on flashing the inertia update.