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Steve, BMW Expert
Category: BMW
Satisfied Customers: 25227
Experience:  BMW Expert
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I was wondering whether you could give your professional

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I was wondering whether you could give your professional opinion on what kind of damage the car could have sustained from an accident.
Car: 2002 BMW 745i with six-speed electronic automatic transmission
While I was stationary at a train crossing and the parking gear selected, but not the electronic parking engaged, another car has come and hit me from behind and there was a huge noise from underneath at impact. The car has broken down 2 miles after the accident and had to be towed away with skates. There was even a larger noise this time when the car broke down. On inspection there has been a gearbox fault found but also a camshaft position- timing over-advanced fault showing on scanner. Hardly any damage has been taken by the rear bumper. In your opinion what do you think has happened? Do you believe the damage to gearbox and engine chain could be accident related?
what faults exactly are stored in the car's fault memory?
Customer: replied 2 years ago.
Faults that are stored:
P0491-secondary air injection system insufficient flow bank 1
P0024 b camshaft position - timing over-advanced or system performance bank 2. Right after the accident the gear would not change to 3rd from 2nd as the revs went up. Thank you
I will provide an honest answer. I trust this will be appreciated.
Please remember that a low rating PUNISHES me for being honest and that I receive nothing for my time until a positive rating is clicked.
the camshaft issue could simply be the sensor or a problem with one of the solenoids. it isn't likely to be an actual timing issue and isn't likely connected to the
the air system fault is likely a failed valve or hose, or possibly clogged air passage unrelated to the accident
as no transmission fault is present, it is very difficult to know what kind of fault could have resulted. these cars are common to leak transmission fluid on the electrical connector, so that is one possibility. An internal mechanical failure due to the impact could be another.
ultimately it will need to be checked hands on with a proper BMW diagnostic tool to verify, as a P code reader is not sufficient to fully diagnose this car.
Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle.
Customer: replied 2 years ago.
Thank you for addressing the engine faults and air system fault. Is there a possibility that the parking pawl could have broken and in turn blocked the gears to change as the car was on parking gear but not brake? I was wondering whether the possibility of the gearbox breaking can in turn damage timing chain? It is surprising for 3 things to all break at once. The gearbox fault was noted at a different inspection by a accident specialist who did not report me fault codes but just the fact that a gearbox fault was found. I was hoping that you could deduce with the information given so far what the possible damages to the gearbox could be.
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I am sorry but as I am sure you can appreciated, simply knowing that "a gearbox fault has been found" in no way allows me to deduce the possible issue.
No, the issue is not likely related to the parking paul, essentially no chance of that.
No, the gearbox cannot damage the timing chain.
The gearbox fault can only be determined by proper hands on inspection and test plans run with a factory bmw tester
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Customer: replied 2 years ago. read under recommendations. Stating that there is essentially no chance of that seems to contradict information out there as "The pawl might also fail or break if the vehicle is pushed with sufficient force, if the parking brake is not firmly engaged."
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I have not been provided with any information which would lead me to believe that the parking pawl would have broken.
1) the car would roll freely while in park if this were the case
2) the bumper would be significantly damaged if the impact was forceful enough to damage the pawl
again, the only way to verify is proper hands on diagnostics and tests with a BMW scan tool.
As the question has been answered, please kindly select a positive rating to ensure I receive proper credit for my time and multiple answers. thank you
Steve and other BMW Specialists are ready to help you
Customer: replied 2 years ago.
1) The car will only roll freely on a slope. The car was on a level road so even a roller skate left freely would remain static.
2) Numerous sources online seem to point out that parking pawls do break off easily, I am sure you are resourceful to find these yourself. Please find attached image of a parking pawl and if that is the only thing holding the car if parking brakes are not on, then as there is so little resistance the force of collision can be transferred into snapping off the pawl instead of damaging the bumper.
if the car rolls freely on a slope or can be pushed while in park, then the parking pawl is bad.
if this information was provided it would have been easy to identify the pawl as bad.
the fact that skates had to be used suggested that the car could not roll at all.