How to Diagnose Ford Focus ST Deflation Detection System?

 I latterly swapped my OEM snowflakes to a collection of 17″ titanium rims wrapped in some new Blizzaks for my iciness setup. I crossed my arms that the inventory TPMS sensors from the titanium would paintings, however I couldn’t get the “deflate till horn honks” process to paintings. So as an alternative of splashing out some money for brand spanking new sensors, or disabling TPMS, I made up our minds to take a shot at the usage of Deflation (*17*) System (DDS) as an alternative. This is the ESC sub-system that makes use of the wheel pace sensors (I consider) to hit upon when a wheel has a smaller circumference than anticipated and cause the tire drive mild. I used to be best ready to in finding two accounts of other people attempting this, one of which reported that it doesn’t paintings, one reported that it does. So I fired up FoCCCus and altered the proper box from TPMS to DDS.

I’m glad to record that it really works flawlessly on my 2021 FoST! I adopted Ford’s parameters of resetting the method within the IPC beneath motive force help and gave it a minimum of 13 miles of ordinary riding to study the parameters. Then I dropped one tire from 35 psi to 20 psi. Within 3 miles of riding, the IPC reported a low tire drive and the cluster mild illuminated.

This is lovely superior. No want to idiot round with which sensor went unhealthy.


Good to know:

In my opinion, TPMS is sweet till the sensors fail or the batteries get started to turn out to be marginal. In my case, I used to be keen to disable them (for off street use, in fact) quite than determine which one is unhealthy, purchase every other one, then pay my tire store to re-mount my blizzak. To do it proper, I might do all 4, which might be an added expense. DDS has been a boon for my time and my pockets. I really like the program a lot better, although it’s much less correct, beneath the “much less is extra” philosophy. Less portions to destroy/exchange, and a suave manner of executing a central authority mandate that’s already doubtful at highest.



Not at the DDS capability, because it nonetheless works flawlessly, however quite in regards to the TPMS sensors from my 17″ (*20*) rims. With an Autel MaxiTPMS TS401 reader, I showed that the (*20*) rims have 315mhz sensors, and my manufacturing facility snowflakes are 433mhz. This is why I wasn’t ready to get the re-learn process to paintings.


This shocked me, as the edges got here from a 12-14 (*20*) in accordance to the section quantity and design and my FoST is a 2021. I used to be beneath the impact that each one pre-facelift (and perhaps even 2021-17) Foci used the similar TPMS sensors.

Oh smartly, DDS is completely enough. I would possibly stay it energetic even if I go back to the snowflakes within the Spring.


Question: the place purchase the focccus instrument only for this selection.?

Answer: FoCCCus is unfastened. I used an ELM327 cable clone.


I must additionally point out that I restarted the ABS module after enabling DDS in FoCCCus. This is finished at the ABS tab, both the usage of the Reset ECU or Initialize ECU (I will’t keep in mind which, however I believe it used to be initialize) button. This cleared the low tire drive mild. I then cleared any DTCs via Forscan.

So in one of the vital instances I’ve discovered the place other people couldn’t get DDS to paintings, I believe it’s for one of a couple of causes:

1) The “studying” process used to be now not finished as it should be. Start this beneath motive force help -> Deflation Detect (hang till it says “Tire drive saved”), then do a minimum of 13 miles of blended riding
2) Deflated tire state of affairs used to be now not examined for lengthy sufficient. It takes a minimum of 3 miles of continuing riding, and DDS will best hit upon a lack of psi if it’s a minimum of 25-30% of what it used to be when the training process used to be finished.
3) ABS module used to be now not reinitialized as described above.


Ford’s General Service Bulletin referring to DDS:


Question: whilst you proper tire drive, does it routinely flip off?

Answer: It doesn’t routinely flip off whilst you proper the tire drive. The mild will stay illuminated till you re-initialize the training cycle (method data -> motive force help -> deflation hit upon). When I did that, the sunshine became off straight away.


Big thank you to @ Melchior for his contribution.


Thanks to Laurance for enhancing.