TPMS Woes

[Niallac]

Hello all!

I am the extremely happy owner of a very early (Dec 2005) GS300 S190.  As ever, the car runs like a watch and cossets its occupants in silent comfort - with one exception - the incessant soft ping of the TPMS 'check system' warning...

The original sensors lasted well, i bought the car at 10 years old (and 67K, full Lexus service history) and it was another couple of years before the sensors started failing.

I had 2 of them replaced about 2 years ago, and my local Farmers (tyre depot-type place) made a good job - they clone their own generic sensors to match the codes on the existing ones.

About 9 months ago (January in Scotland, surprise, surprise), the TPMS 'check system' light came back on.  I cleared the fault using my OBD tool, and it didn't reappear for another few weeks.  I've been driving it like that until the MOT was due (a month from now).

I took it in for MOT and service (trusted independent mechanic) and he sent it to his own tyre depot to have the dead (#3 according to OBD) sensor replaced.  It came back from his tyre depot with a new (Schrader) sensor, but also a note from them saying they'd been unable to program the new code into the ECU via OBD.  I don't know why they didn't just clone from the old sensor.  This left both the 'check system' and 'low tire' messages on the display.

I took the car into my local Farmers this afternoon.  They succeeded in programming the new ID code into the ECU via OBD, but when they re-initialised the TPMS system, the two error messages remained on the display.  Even stranger, when they then used their TPMS scanner to read the codes from all 4 wheels, all 4 came back with the same ID code - that of the new sensor. They checked the scanner on another vehicle, and it correctly read all 4 unique IDs on that vehicle, then the same -i.e. all 4 same ID code - on mine. OBD however apparently shows the three existing sensors, with their own unique ID codes and pressure readings, and shows sensor 3 as absent (no pressure reading, tyre temp at -40, etc.  

I am beginning to suspect the sensor that my mechanic's tyre fitted is at fault here.

Has anyone else seen this particular, or a similar problem, before?  I will post a couple of photos of the packaging from the new sensor.  The photo label in particular looks dodgy - not sure how clearly it will come out but the quality of printing on the 'EZ -Sensor' part and the photo are poor.

[Sami Tilander]

Are you able to see the live data monitoring of the sensors with your OBD tool? Like with TechStream? Do you see that the three sensors are there and sending meaningful values (e.g. if you let some air out of the tire, that is visible in the readings)? If yes, then that scanner somehow failed to read the IDs...

I've had bad experience with the Schrader TPMS sensors: I once replaced all 4 sensors with new Schrader ones (not EZ series). They worked most of the time ok, but time to time caused error messages (check system). So, I had to swap back the OEM sensor (with new batteries).

[Niallac]

Thanks Sami.  I'll need to get the car onto my OBD scanner asap to check this.  Likely to be a week or so before I get the chance...

[OldTrout]

Niall,

If you are goos with your hands and can solder then replace the Battery in the old dead sensor. Britprius wrote back in 2019:

 

   On 10/10/2019 at 4:46 PM,  Britprius said: 

You do not need to buy a Lexus wheel.
Go t o your nearest small tyre fitter "not quick ripoff". Ask them to replace the tyre monitors on the wheels you wish to work on with standard rubber valves "I would do all four". They do not need to take the tyre off to do this. Just break the bead on the valve side of the wheel, undo the outer nut that holds the monitor valve in place, remove the monitor valve, and replace with a standard rubber valve. the tyres can then be re-inflated no need to balance since the tyre has not moved on the wheel.
You can now use the car, and repair the monitors at your leisure. Spray the outside of the valve monitor nuts with WD40 the day before you do this. This will stop the top of the valve possibly breaking off when undoing the nut. You can if you wish slacken off the nut half a turn then re-tighten to the same position. 

When the monitors are repaired do the same again to re-fit them. My friendly tyre dealer did this for £5 a wheel including the rubber valve. The car will not require the monitors to be programmed because they are already registered. Nor does it matter which wheel the monitors go in, but if you keep a record "a note in the handbook" of which registration number is in which wheel if you use Techstream it will tell you which wheel has a problem in the future. If you change wheels round do not forget to alter your note accordingly.

Your total cost should be no more than £6 or £7 per wheel including batteries.

John

[Niallac]

Thanks John.

Once I get it onto OBD, I'll have a better idea of which route to take to get a clear diagnostic picture.  If I think the new transmitter is the problem, I will just get my own tyre place to put another of theirs in.  Not ideal cost-wise or environmentally, but time for maintenance is a problem just now - especially as the motorbike cut out on me on the way to work this morning... 😂 I will post an update as soon as I have one.

Cheers, Niall