Tyre pressure reset failure

[Paulfromfrance]

Hi there!
I come here to expose a problem that nobody around me was able to solve until now. Here is the context :

I own a 4.8is from 2005 which used to work perfectly until I had a small accident.
I bumped a curb and damaged :
- my front left rim
- the ride height sensor
- a lower arm was folded
- Steering rod broken

I did the following things:
- rim repairing
- ride height sensor replaced
- wheel bearing replaced
- lower arms replaced
- steering rod replaced
- 4 new ABS sensors
- New geometry

But since:
- It drives normally but every each 40 miles approximately, my tire pressure warning lights in yellow. Then I stop the engine, restart it and do the reset procedure by pressing the tyre pressure button for severals seconds (as described in maintenance book, and as I was used to do successfully before the accident) but since nothing happens : the warning light stays.
- If I wait for approximately 30 seconds before restarting the engine, the warning light disappears at engine start… (but reappears 40 miles later).

My concern is that I fear to damage something in my car (differentials, transfer box, or gearbox) if keeping driving with this failure.

Additional clues :
- My X5 has NO pressure sensors in the wheels. It detects possible pressure failures by comparing each wheels turns.
- I checked many times my tyres pressure, they are perfect.
- I tried to mount my winter wheels to exclude my summer wheels as a cause, the problem is exactly the same.
- The reset button itself works, because when keeping pressing it before starting, it lights the tyre pressure symbol in yellow, then in red, before disappearing. But the reset procedure fails as described before.
- It seems that when I drive under 60 mph the warning doesn't light. I already drove several times for 100 miles approximately on small limited roads without having the warning signal. But on highways at 80 mph (French limitation), which represent 90% of my trips, the warning lights EACH TIME after +/- 40 miles.

As said before, no mechanical around me is able to solve it, and have even absolutely no idea about a possible cause, that's why I came to your community which seems to be very wise regarding tricky problems. So I would be really grateful to any one of you who could help me to solve this trouble.

Best regards,

Paul, from France.

[andrewwynn]

New ≠ fixed. Your symptom suggest one or more wheel sensor is not reporting correctly.

Why'd you replace all four if only one affected?

Did you use OEM brand?

Do you have a scanner that will show you real-time wheel speed. See if you can find a speed where one wheel shows different value. Usually the computer will only report whole or half numbers but maybe at 60.0 m mph or xxx rpm you can get three to agree and one is different.

[Paulfromfrance]

Originally Posted by andrewwynn

New ≠ fixed. Your symptom suggest one or more wheel sensor is not reporting correctly.

Why'd you replace all four if only one affected?

Did you use OEM brand?

Do you have a scanner that will show you real-time wheel speed. See if you can find a speed where one wheel shows different value. Usually the computer will only report whole or half numbers but maybe at 60.0 m mph or xxx rpm you can get three to agree and one is different.

Hi andrewwynn,

Thank for your reply.
First I changed only front left abs sensor, and the trouble was there.
Then I changed the three others, with new original BMW parts.
I don't have access to a wheel speed scanner.
Even if one sensor sends a wrong information, it doesn't explain that the computer refuses to reset the system, no?

[wpoll]

Originally Posted by Paulfromfrance

... Even if one sensor sends a wrong information, it doesn't explain that the computer refuses to reset the system, no?

That is the perfect explanation...

[Qsilver7]

Here’ some info about the RPA (flat tire monitoring system) on the e53 X5:

[andrewwynn]

From the description above describe more accurately what's happening. Eg color of indicator b and Bing sound etc. Any written message.

You can't do serious DIY repairs without a scanner. The best for e53 is the foxwell nt510 or nt520. They can be found on eBay very reasonable

[Paulfromfrance]

Thank you very much for these precious informations. I forward them to my mechanical.