Member
Hi everyone,
im having trouble with my car lately.my car is a 2002 540i automatic with about 122000 miles.
after driving the car for a couple minutes and the transmission warms up it starts slipping and immediately puts me into limp mode.when I turn the car off and let it sit for a while and turn it back on it doesnÂ’t go into limp mode right away but after driving a 2 or 3 miles trans failsafe progress pops up and it gets stuck which i believe is 4th gear. It never throws a cel but once when I brought it to a shop to take a look at it and it threw a p0721 output speed sensor 1234.the guy said to bring it to a transmission shop so they changed the sensor and fluid(I already changed the filter and fluidit myself when it first happened).
the guy showed me the sensor it was burned and thought for sure that was the culprit but after a test drive it went into limp mode again after like 10 min of driving.
so he says the transmission is shot and I need a new one......
well i still didnÂ’t believe it was the transmission so I changed the oil cooler(heat exchanger) and the thermostat because I thought maybe one of them failed and the tran overheats.
well the problem persists.....
I should mention that the previous owner had the “lifetime “ fluid changed at like 30000 miles for whatever reason and before I changed it again the fluid was black and burned and has been in there for almost 90000 miles..🤔.they didnÂ’t use a gasket but sealant🤨.the magnets in the pan were covered in metal shavings..so it was leaking and I PUT LUCAS OIL LEAK STOP in it and thatÂ’s when it started to go into trans failsafe mode.
i put a lot of money into the car because it was in rough shape and neglected so if anyone has an idea if itÂ’s not the transmission thatÂ’s bad but something else IÂ’d really appreciate any thoughts on this.
i read about alternator and battery problems being the culprit but it literally only happens when the transmission warms up....🧐
thanks in advance (sorry for my bad English)✌️
Member
The ZF 5HP24 has a known weakness in the A drum in the transmission.
There is a locking ring that clips into the end of the drum, and the design is such they the end of the drum after the ring breaks away.
There is a stronger aftermarket replacement with an improved lock ring design, but the transmission still needs to be rebuilt to repair it.
I just made a 6 speed manual. Conversion when mine had this issue, and I never once regretted it.
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Member
Yeah I’m afraid I gotta get it rebuilt I just don’t know if it’s worth it because the timing chain guides are due too.
Again it only happens after I drive for a couple of miles and also reverse works just fine I just felt maybe there’s something clogged inside the valve body.they flushed it but idk if that would free those tiny passages inside the tranny.
well I’m honna ask the guy for a quote tomorrow but last time he said after it’s all done I have to get the car to a bmw stealer to get it reprogrammed is that correct?
Member
No.
Only if you're messing with the control modules themselves, or changing to manual.
A straight rebuild or replacement of your transmission won't require any coding.
Ultimately, the decision is up to you. Do you value the car enough to have it repaired. Once the timing chain guides and associated work is done, and the transmission rebuilt with the upgraded A drum it'll be entirely likely the car will last you another 20 years before you'll have to look at it again if you keep the maintenance regular.
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