Solving why all four our BMW 435i’s TPMS sensors failed at once

This one felt like it should have been easy to solve. In the end, maybe it was, and maybe it wasn’t.

“I feel like the problem is gone but I don’t feel that satisfying feeling that we ‘solved’ it,” says BimmerWorld’s Phil Wurz after we seemingly rectified a recent electronic situation.

So, what actually happened? Let’s back up a little and describe our BMW 435i’s recent failure mode and our path to “repair.”

After we solved the recent boost leak issue–human error, always a straightforward fix–we were out on a test drive.

And the TPMS warning went off. Like, WENT OFF, went off.

[Our BMW 435i boost leak was easy to spot but challenging to fix]

Not only did the dash signal us that there was a TPMS error, the message stated that the car had lost contact with ALL four TPMS sensors.

We tried to perform a TPMS reset, but the system never found any of the sensors. The reset meter stayed at 0% before ultimately timing out and giving us the “Uh, I can’t find any sensors” message again.

Our Foxwell scan tool indicated two “permanent” error conditions with the TPMS system, indicating that they could have occurred at any time and were not necessarily current, although they both seemed relevant.

One message indicated, “Tyre pressure monitor: wheel recognition when starting, calibration not possible.” The other read, “Tyre pressure monitor: wheel electronics, no reception, rear left.”

Despite the warning about the rear-left sensor, the system still couldn’t find ANY sensors, so it would just continue on with that TPMS error indicating on the dash.

Now, you may be saying, “Hey, don’t sweat it, just check your pressures with a tire gauge.”

Well, the problem here is that BMW outsmarts you: The car won’t let you shut off the traction or stability control if it can’t get an all-clear from the TPMS system. That means no track fun until this situation was rectified.

We got Phil on the Batphone and discussed our situation.

After some googling and discussions among the BimmerWorld crew, we found out that BMWs occasionally do this–the whole losing-all-the-TPMS-sensors-at-once thing–and the point of failure is typically the antenna module that receives the TPMS signals.

We didn’t really suspect our sensors themselves as they had all been replaced less than a year ago, and what was the chance that all four would fail simultaneously?

So we ordered up an antenna and replaced it, which was kind of pain in the butt as it’s located under the rear package shelf and requires the removal of a bunch of rear trim, as well as crawling around our JP Marketing roll bar to remove the shelf trim so we could, finally, access the module.

It wasn’t enough of a pain to remove the roll bar, but we do recommend stretching and taking all the tools that you think you’ll need before climbing in, because it’s not something you want to do multiple times.

With the module replaced, we headed back out for a road test. The car seemingly found the sensors and began performing a reset of the TPMS system.

The reset progressed to 49%–and then froze. It hung at 49% for a while before showing the message stating that, again, no sensors could be found.

So, uh, we were a bit stumped at this point. We called Phil again and discussed options.

Just to rule out the sensors, we ordered new ones all the way around. BimmerWorld hustled some down to Florida, we peeled back our Vitour P1s just enough to swap out the sensors before hitting the road again.

The car once again began a TPMS reset, with the numbers climbing steadily to 49%, then stopping again–before jumping to 53%, 58%, then climbing rapidly to 100% and finally showing current pressures and indicating a functional system. We really could have used a quicker run through 49%, but our BMW really seemed to want to prolong the drama.

So, yeah, it’s “fixed.”

But you see why we and Phil don’t feel fully satisfied that we solved this mystery. The likelihood of all four sensors pooping out at once still seems astronomically low, and it just feels like there’s more variables at play here.

So we look to you, gentle reader, for any wisdom. Is there a failure mode that neither us nor BimmerWorld could find a record of stating that a single TPMS sensor failure causes a complete system disconnection? Is there another failure mode that we should be exploring just to make sure we actually fixed this and it didn’t just fix itself?

Or should we just take the W and move on and never question our good fortune lest we tempt the fates of Munich? We’re eager to hear your opinions or knowledge.

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