TPMS Check System message and tire pressure light on

[care_mentor_288]

My 2007 Lexus RX400h tire pressure light has been on constantly for awhile and I can't figure out why.

I've had all of the tire pressure sensors replaced, and programmed, and they read as working (with the correct pressure).

I've tried both main and 2nd tire sets. 

 

I'm stuck and would appreciate some advice about how to fix this. 

 

Here is what the dash looks like whenever I'm driving:

 

I took the car to a tire shop and got the sensors checked and programmed:

 

I took the car to Firestone Autocare and had a diag check done and they said the sensors were the wrong frequency, but that isn't correct because it was the same problem with the old TPMS sensors that I got replaced and the frequency in the diagnostic photo is the same as what they recommended.

The other day I got a flat while on a bumpy road and almost didn't figure it out quickly because the TPMS wasn't working. I did pull over just to be safe and am glad I did, but I think most people wouldn't have noticed for a while.

I read the TPMS diagnostics etc. - PG001_07.pdf (the 2007 rx400h isn't covered) but the only thing I can figure out is where it says "Refer to the diagnostic procedure for checking the TPWS ECU and/or antenna/receiver located in the applicable Repair Manual on TIS." but when I poke around on the internet I get past my head. Maybe it's related to service bulletin L-SB-0025-09 (Tire Monitor System - 'Lost Communication With ECU' Mssg https://workshop-manuals.com/lexus/rx_400h_fwd/v6-3.3l_(3mz-fe)_hybrid/sensors_and_switches/sensors_and_switches_steering_and_suspension/sensors_and_switches_wheels_and_tires/tire_pressure_sensor/component_information/technical_service_bulletins/customer_interest_for_tire_pressure_sensor/sb0025-09/mar/09/tire_monitor_system_lost_communication_with_ecu_mssg/page_1358/ )

[RX400h]

Have you tried a Lexus dealership? 

[care_mentor_288]

Just now, RX400h said:

Have you tried a Lexus dealership? 

$285/hr for a diagnostic... They said they'll probably recommend replacing the TPMS sensors right away and that would be ~$700+ 

[dgorrie]

Might have missed it, but do you have a spare tire that might have a TPMS sensor?  

[care_mentor_288]

2 minutes ago, dgorrie said:

Might have missed it, but do you have a spare tire that might have a TPMS sensor?  

Good question, thanks for checking. I do, but the sensor was showing as working, reading the right pressure, and programmed too. I wish it was that easy!

[HaloRomeo27]

I have a tool that can read twice as much information that tool is reading and as always launching a parts canon never ends well I would have diag the issue before the sensors were replaced honestly it will take a high end scan tool to correctly diag those sensors and the ecm that controls them and did you replace them with OEM the only ones I found that work correctly is Denso you can get those on Amazon for about 50 dollars for one 

[HaloRomeo27]

And if the old sensors were not deleted from the ECM before the new sensors were added the ecm is most likely confused I guessing they were not programed correctly or there not the correct sensor not sure if you took a picture of the new ones before they were installed as I would be able to tell you if there correct 

[RX400h]

16 hours ago, care_mentor_288 said:

$285/hr for a diagnostic... They said they'll probably recommend replacing the TPMS sensors right away and that would be ~$700+ 

Another possible option is a Toyota dealership. I have saved hundreds of dollars by having them service our hybrid which has an identical powertrain as the Toyota highlander of the same era.

[care_mentor_288]

Thank you @HaloRomeo27! This is really helpful and such a good point. The "Check System" problem was there with the old TPMS sensors and I think they just replaced them and didn't do a diagnosis other than with a cheap machine. 

My friend replaced them at a cheapo shop, and I doubt they had a good machine for diagnosing. (He borrowed my car for a month and that is how he paid me back) 

When I took it to another cheap shop just to make sure the sensors were working and programmed, the first time the sensors failed to relearn, but the second time they said the learning was Okay.

I think I saw that the TPMS receiver is near the center of the car. I don't know if it is related, but my backseat overhead dome light has been finicky. It flickers on and off when I turn it on or have it on door mode (I usually leave it off).

Thank you @Rx4000h for the suggestion of going to a toyota dealership! 

I could take it back to the shop my friend got the sensors replaced, they said they'd look at it for free, but I don't know what they could do differently since they didn't do it right the first time. 

I'm not sure what else to try at this point, so that is probably the next step. (or just forget about it and live with the light on and save the $$)

Thank you both for the advice so far!

First try programming the sensors failed:

Second try, relearn Ok
  

[HaloRomeo27]

Most cheaper tools will read the sensors but not what the ECM is reading so the tool will show everything fine but in the ecm it will not as far as the dome light that is a loose bulb 

[care_mentor_288]

Thanks @HaloRomeo27!

Would I be able to fix the problem by borrowing (or buying) a more expensive reader tool, or would that just help me know what the problem is but still need a dealership to fix it? 

I could probably borrow one from a friend or maybe even buy one for the same cost as an hour at the lexus dealership. 

What tool(s) would your recommend trying?

Thank you again!

[HaloRomeo27]

I have sevral diag tools the cost is way more than a dealer diag my tools cost around 5,000 for each one as there is different tools for diag not sure how far you are from me if u was close I would be more than happy to diag the issue there is a few things we can check when you have the time 

[HaloRomeo27]

Did your tool come with a cable to connect to the OB2 port ?

[care_mentor_288]

Thank you @HaloRomeo27! That's really kind, but I'm across the country on the West Coast.

The OBD autel handheld the tire shop used did use an OBD2 sensor (I'm almost certain)

I think Toyota dealership should be my next step.

[HaloRomeo27]

Yes the Toyota dealer has the daig tool as lexus they use tech stream I like the software it only works on Toyota or lexus my subscription for that cost me about 2,000 a year but worth it and is the only way to get the latest ECM updates 

[BriVan]

HI @care_mentor_288 , was your issue ever resolved? I am having the same issue. What did Toyota say?

[HaloRomeo27]

that warning is most likely a bad sensor in one of the tires do to battery that is the most common less common is the sensor is not correctly added to the TPMS system 

3 minutes ago, BriVan said:

HI @care_mentor_288 , was your issue ever resolved? I am having the same issue. What did Toyota say?

 

[care_mentor_288]

I think @HaloRomeo27 knows best, it is probably that the sensors went bad, then they were replaced with non-oem sensors and not programmed properly.

I called around and basically, it was going to cost $200+ to have diagnosed at a lexus or toyota dealership and then they'd suggest replacing all of the sensors again ($750+) so it didn't seem worth it to me considering the current state of this car.

If the light just started I'd get new TPMS sensors from somewhere reputable, if you've just had the sensors replaced & the issue is still there, I'd then look deeper like @HaloRomeo27 suggests.

 

[HaloRomeo27]

My scan tool basically reads all the sensors and tells me which one is not working correctly if you want new sensors I highly recommended OEM replacement you can order them though a local dealer there about 90 dollars US for 1 so about 400 if you replace all 4 add another 100 if your spare has one then they still need programmed after there install this is where the dealer pretty much bends you over 

[HaloRomeo27]

Now since I have this error on my Lexus and I am not replacing the sensors till I get my tires rotated I will post the diag info here and pics so others can see the issue 

[HaloRomeo27]

Ok I decided to share how to change a tire sensor if your on a budget and have the scan tool to program them now I don’t recommend you do it this way but if your in a bind and want to save money than this works I added the basic diagnostic so you can see and follow along if you anyone has questions feel free to ask me I will do my best to help I use Denso sensors from Amazon never had an issue with them 

[care_mentor_288]

3 hours ago, HaloRomeo27 said:

THANK YOU! This is very helpful.

Quick question, how do you know which setting to use? It looks like the option above the one that is selected would be the correct years as well for the 2008RX 400h?

[HaloRomeo27]

The highlighted selection is only for a reference and yes the selection above is the correct option as the J is for Japan models most of the older Toyota and Lexus use the 315MHz I just did a quick post on the TPMS did not go to in depth with it I can say I prefer the autel tool over techstream at least for reprogramming and testing 

[HaloRomeo27]

Thought I would also mention there is a push button on the passenger side under the glove box that selects which set of tires you are using make sure it is plugged in and that button is in the correct position