TPMS registering to wrong wheel in PCM

[DWH]

I have just bought a 66 plate SD on 20”, from a non OPC ‘prestige car specialist’ (their words). I am really enjoying it but struggling with the TPMS which seems to be reporting the pressures for the tyres which seem to be out by 90 degrees anti-clockwise!
Having rechecked and reset pressures several times to the prescribed 20” pressures of 33F and 36R the pressures are mapping as below and attached pic.

FR pressure is displayed on PCM as FL
FL is displayed as RL
RL is displayed as RR
RR is displayed as FR
This results in PCM TPMS screen showing the left of the car as 33 and right of car as 36….this also then triggers the warning of the rear left being 6 psi under inflated.

I have run the full TPMS set up as wrong type ie 19” and Full load and back to 20” but each time comes back the same…..

The dealer had fitted new tyres all round and I noticed on the test drive that the MFD was showing ‘TPMS Error, Service required’. I pointed this out and they said they would fix it, which they did clear.

The car was set up to show pressures in bar, which didn’t mean much to me, and it was a few days before I got to playing with the PCM and switched to it to PSI, when it showed the dealer had overinflated them as all four tyres were over 40, so reduced it to where it should be. I’m not sure if they screwed up tyre/sensor refit that would cause this!
Any ideas as to how to correct this annoying issue - I don’t know how each tyre pressure monitor registers to the correct corner in PCM! Any advise gratefully received!

[Connoisseur]

imho they cleared the fault code but they haven’t yet fixed the problem. Back to the Dealer to sort on that one. Does your car have same wheel/tyres front and back?

[Connoisseur]

……different sizes front to back on S so Dealer will need to sort, probably by fitting correct sensors/wheel combination.

[B737NGWS]

My guess is that they have either:
Replaced original TPMS with aftermarket ones which will require coding for each wheel?
Swapped TPMS around and confused the system?
I guess you have tried a full re-set when the car is stationary?
Maybe a return visit to supplier or they can pay for OPC reset?

[andywebber]

I think that you probably already know this, but with my limited understanding of these things from my BMW, the garage need to pair the TPMS sensor to the appropriate corner of the car using the appropriate code scanner / programming / coding tool (the official Porsche one is called PIWIS).

It only takes a matter of minutes, but I guess that if they do not have the appropriate coding tool they can simply manually move the wheels across and check

HTH
Andrew

[B737NGWS]

It seems very strange though, as the wheels are offset (wider at rear) they would have had to change the sensors around if they are still the originals? Not sure you would need to completely remove sensors to change tyres but anything is possible I guess?
Be warned though OEM TPMS from Porsche VERY EXPENSIVE!

[Madelvic]

I wonder. Have the wheels been refurbished? Could the TPMS sensors have been removed and then put back randomly?

[DWH]

Thanks for everyone’s input…..AFAIK the wheels are those it had from new, and are standard (for the 20” option) of 265/45 at the front and 295/40 at rear so no confusing front/rear, although they are completely unmarked, so may have been refinished, but the rest of the car is equally unmarked, so hopefully just had a careful owner!
The car was at 33k miles and nearly 5 yrs old when sold, and as the dealer wasn’t an OPC, they fitted cheaper tyres. My limited research of TPMS suggests that sensors have non replaceable batteries with a life span of ~3-5yr, so wonder if they fitted non OEM (and much cheaper) TPMS sensors, which need mapping to each wheels position, but screwed up the mapping…..
Someone with more TPMS knowledge may know if there is any logic to that….. it’s booked in to the dealer to sort but could do without the hassle if possible.

Thanks

[SAC1]

Those are budget brand Korean made tyres. They will not be Porsche approved "N" rated.

[Madelvic]

This from the Porsche workshop manual (suggestion is the dealer will need to reset using the PIWIS tool)

WM 4X00IN GENERAL INFORMATION ON TYRE PRESSURE MONITORING (TPM) (ALL MODELS) > GENERAL INFORMATION ON TYRE PRESSURE MONITORING (TPM) > DESIGN AND OPERATING PRINCIPLE > DESIGN
Fig 1: Identifying 3RD Generation TPM System Design
Courtesy of PORSCHE CARS NORTH AMERICA, INC.
The 3rd generation TPM system consists of:
4 wheel electronics units screwed onto the wheels
4 TPM valves and
1 TPM control unit (KSG) with integrated central antenna (installed on the rear axle)

WM 4X00IN GENERAL INFORMATION ON TYRE PRESSURE MONITORING (TPM) (ALL MODELS) > GENERAL INFORMATION ON TYRE PRESSURE MONITORING (TPM) > DESIGN AND OPERATING PRINCIPLE > OPERATING PRINCIPLE
The 3rd generation TPM system operates on the principle of unidirectional communication between the wheel electronics and control unit. This means that the wheel electronics can communicate with the control unit, but the control unit cannot communicate with the wheel electronics.
The wheel electronics units send the currently measured tire pressure, the direction of rotation, the temperature of the air in the tire and the remaining service life (of the battery) as well as a specific ID from the wheel that is currently turning at specified intervals.
The wheel position is learned automatically from the side and axle specifications. The direction of rotation of a wheel is detected by acceleration sensors in the wheel electronics (left/right detection). Axle sensing (front axle/rear axle detection) is performed based on differentiated sound levels between the front and rear axle, where the central antenna is fitted close to one axle (high level). The levels received from the other axle are correspondingly low.

WM 4X00IN GENERAL INFORMATION ON TYRE PRESSURE MONITORING (TPM) (ALL MODELS) > GENERAL INFORMATION ON TYRE PRESSURE MONITORING (TPM) > DESIGN AND OPERATING PRINCIPLE > TRANSMISSION MODES
The wheel electronics units communicate with the control unit in various modes. Depending on the current mode of a wheel electronics unit, it sends telegrams to the control unit at defined intervals.
Normal mode: Normal mode is active while the vehicle is driving (after Burst mode has ended).
Sleep mode: Sleep mode is activated as soon as the vehicle remains stationary for longer than 5 minutes. The wheel electronics then send no more telegrams. If the ignition is switched on while the wheel electronics units are in Sleep mode, no tire pressures are displayed (display in instrument cluster: "-.-"). Tire pressures are only displayed again when the vehicle is driving (see Burst mode).
Burst mode: If the wheel electronics units are in Sleep mode and the vehicle is accelerated to over 25 km/h (15 mph) from stationary, the wheel electronics units switch to Burst mode. The wheel electronics units send their telegrams for 60 seconds at fast intervals.

WM 4X00IN GENERAL INFORMATION ON TYRE PRESSURE MONITORING (TPM) (ALL MODELS) > TEACHING TYRE PRESSURE MONITORING (TPM) > GENERAL INFORMATION
If a new set of wheels is used or wheel electronics units were replaced, the TPM system must be taught. When teaching the TPM system, the control unit stores the wheel IDs of the wheel electronics units and assigns a position to them.
New wheel electronics units can be taught by selecting a new set of wheels in the instrument cluster.

The system is then in learning mode and re-assigns the wheel IDs that are received.
But the system also detects a wheel change if the stored information does not correspond to the information received. The control unit then displays a message on the instrument cluster prompting you to select the newly fitted set of wheels.
The wheel electronics units can be taught while the vehicle is driving and while it is stationary. Teaching while driving is recommended.

WM 4X00IN GENERAL INFORMATION ON TYRE PRESSURE MONITORING (TPM) (ALL MODELS) > TEACHING TYRE PRESSURE MONITORING (TPM) > TEACHING WHILE DRIVING
A procedure in PIWIS Tester II 9818 can be used to teach the wheel IDs while driving: >>Tyre Pressure Monitoring (TPM) system << >>Maintenance/repairs<< >>Teach wheel IDs<< >>Teach wheel IDs while driving<<.
The wheel IDs can also be taught without using the System Tester. The following points must always be observed:
Allow an idle time of at least 5 minutes before teaching the wheel IDs (wheel electronics units are then in Sleep mode).
Briefly accelerate the vehicle to over 25 km/h (15 mph) in order to teach the wheel IDs (wheel electronics units are then in Burst mode).
Then continue driving at any speed (even < 25 km/h or 15 mph) for max. 10 minutes.
Teaching was successful if a pressure reading is displayed in the instrument cluster for all wheel positions.

WM 4X00IN GENERAL INFORMATION ON TYRE PRESSURE MONITORING (TPM) (ALL MODELS) > TEACHING TYRE PRESSURE MONITORING (TPM) > TEACHING WHILE STATIONARY
Information
If the TPM system is to be taught while the vehicle is stationary, it is advisable to take note of the wheel IDs and the position of all wheels and store the information together with the wheels. This can significantly reduce the teaching time for the next wheel change.
The wheel IDs and position can be read out using PIWIS Tester II 9818 if this information is already stored in the control unit. >>Tyre Pressure Monitoring (TPM) system<< >>Actual values and input signals<<

WM 4X00IN GENERAL INFORMATION ON TYRE PRESSURE MONITORING (TPM) (ALL MODELS) > TEACHING TYRE PRESSURE MONITORING (TPM) > TEACHING WHILE STATIONARY > IF WHEEL IDS ARE KNOWN
Allocation of wheel electronics units using the PIWIS Tester II 9818: >>Tyre Pressure Monitoring (TPM) system<< >>Maintenance/repairs<< >>Teach wheel IDs<< >>Teach wheel IDs while vehicle is stationary<< >>Wheel IDs known<<.

WM 4X00IN GENERAL INFORMATION ON TYRE PRESSURE MONITORING (TPM) (ALL MODELS) > TEACHING TYRE PRESSURE MONITORING (TPM) > TEACHING WHILE STATIONARY > IF WHEEL IDS ARE UNKNOWN
Allocation of wheel electronics units using the PIWIS Tester II 9818: >>Tyre Pressure Monitoring (TPM) system<< >>Maintenance/repairs<< >>Teach wheel IDs<< >>Teach wheel IDs while vehicle is stationary<< >>Wheel IDs unknown<<.
Always observe the following procedure (instructions on the System Tester always take precedence!):
Allow an idle time of at least 5 minutes before teaching the wheel IDs (wheel electronics units are then in Sleep mode).
As per instructions on the System Tester, pressure (at least 0.2 bar and approx. 5 seconds) at the wheels must be reduced.
The wheel electronics registers the pressure difference (after 2 minutes at the latest) and switches to Burst mode.
The control unit receives the telegrams from the activated wheel electronics unit and writes its wheel ID to the specified position.