Har har ... next should be B8
I know a cool parts manager who knows the job and has gotten odd parts for me ... and independently found the same part number
This is a discussion on TPMS issue within the CLA Wheels and Tires forums, part of the Mercedes-Benz CLA Forum category; I thought they only steal rims/wheels. Them nitwits steal just the tpms nowadays?? Kidding aside, are the sensors brand new? Maybe some initialization required on ...
Har har to you too
Supposedly there is no relearn process just drive to activate sensors and the receiver is supposed to adapt (like when tires are rotated it reset itself)
Hate to bug the dealer just to have them reset and then same issue
Was hoping someone had the same issue and can share their fix (if one exists)
OK figured it out !!
Found a tiny little hidden line in some tpms tester manual noting >45psi is needed to “wake up” new sensors so they start sending (like duh!)
Once they start talking then one finds out they each have a unique “name” ... these little talkative babies have funny names like 08 B2 68 20 etc
In my case the old names were still assigned within the tpms subsystem so I had to muck around and update the sensor names for each corner (which is how it knows which psi reading goes where for the display how cute)
And voila the numbers are back!
Of course my case is complex cuz the error message was locked in and stored so I had to go through and fix the hard way - geewhiz if only I knew sooner about that “wake up” trick?
In the future ... set new wheels to 50psi and roll around the block ... that should tell the system to listen for new sensor names and auto update (which makes sense since it updates sensor names after rotations)
Now ... I wonder if there is a “calibration” routine cuz it seems these sensors readout high by 1.5~2psi
Yeah yeah yeah I am such a GFP
FYI ... the "calibration" part is a bit of road experience, and a bit of data ... so like I trust my pressure gauge as over the past 5 years its data makes sense ... e.g. 35.5; 36.0; 36.5psi for the fronts as read by the gauge correlate very well with corresponding changes in tire wear. Case in point is the factory says 36psi front, 32psi rear for my FWD. So far the tread has worn down very flat across the entire pattern, with a little cupping in the middle as expected. So the pressure gauge data seems trustworthy, and usually taken between 65~75F within the garage for some consistency.
The original tpms sensors were pretty darn close to what my pressure gauge said ... like 35.5psi in the garage on the gauge would yield 36psi in the display within 2 minutes of driving out. So those were good.
The new ones, despite being the same Schrader device (and per my other TPMS sensor info post about all the FCC gibberish I know these MRXGG4 units are one of the 0009050300 parts used at dealers) seem a little happy ... by about 1.5~2psi it seems?
Oh well ... yet another diy calibration trek coming up ... 8-)