Tyre Pressure Warning Light - Can't See Forest For The Trees!

[Deep Blue]

Okay,

2009 VW Passat CC 2.0L TDI (CBBB engine).

The tyre pressure warning light (on speedo) has been on for a week now - starts flashing (amber) when key put in and car started, then after 30s or so it just stays put on the dash (amber).

Tyre pressures all fine (have checked) and have tried re-setting with switch on centre console to set on high and low pressure settings - makes no difference.

Have read a bit about this here and elsewhere, but I get a bit muddled with all the info on how to fix this "non-critical" but annoying problem...

So, used Foxwell scanner (don't have VCDS) and get:

"Tire Pressure - 01521 - Sensor for Tire Pressure - sporadic 004 - No signal/communication"

Now, not quite sure how tyre pressure is sensed on each wheel and what needs to be done - read about older style direct TPMS and newer style indirect TPMS (uses ABS sensors on each wheel to measure rotational speed - flat tyre rotates more than others). Is there a step-by-step process of elimination to follow in order to find the suspect part/s?

Hope someone can shed some clarity on this.

Thank you for any help/assistance.

[kamold]

Your tyre pressure sensors have batteries in them. They are at the end of the useful life.
You'll need to replace the sensors, the batteries are embedded in them.
Passat has direct TPMS using sensors in the tyre stems, with the receiver integrated in the CCM behind the glovebox.

[Deep Blue]

Fantastic Kamold! What a relief! I guess then one of them has failed - flat battery resulting in sporadic signal. Would make sense to replace all four?!

So, just buy 4 sensors on eBay then and install? Do you know what the part number is?

I assume it's an easy job? Just remove each wheel and replace each sensor? Is there a pic somewhere or a guide?

[Deep Blue]

Ah! Checked a parts website - c.$200 per sensor! Yikes! So, including spare wheel that's c.$1000!

[Deep Blue]

Know a bit more now - looks like wheels off, tyres deflated and then break bead on tyre to get to sensor - inside wheel? Maybe more trouble and expense than it's worth?

[The_Hawk]

Presumably you could disable TPMS in VCDS until you get to replacing the sensors to make that light go away.

[Deep Blue]

Have a Foxwell (not VCDS) - will need to check if I can disable.

[The_Hawk]

Have a Foxwell (not VCDS) - will need to check if I can disable.

I've never used Foxwell (have VCDS) but these instructions might lead you to the right place, essentially you're telling the car the option isn't installed.

This bits might not be quite correct depending on the model and software, but you get the idea.

TPMS off (light)
19-CAN Gateway
07-Coding
Coding Helper ----> Scroll down and check/uncheck 1 box


TPMS off (message)
46-Central Conv.
07-Coding
Coding Helper ----> Scroll down and check/uncheck 1 box

Source: VWVortex.com - how to disable tpms in mk5?


One thing that is mentioned in that thread is turning on the passive version which works on the rotational speed of the weels and is what models without pressure sensors do. I was looking at turning it on in my Golf, but without the reset switch you would need to pull out VCDS (or similar) every time it needed resetting... but you have the button so that might be your better option. The passive system isn't as sensitive as having dedicated sensors, but it's something.


This was the instructions for turning on the indirect TPMS (for the Mk6 Golf at least which is likely similar if your car has the required bits) :
How to: retrofit indirect Tire Pressure Monitoring in 5 minutes. (7K6)

[kamold]

You can get a whole set for $200. Check Ebay.
They are 433MHz sensors.

[Deep Blue]

Ah, eBay - 433Mhz. Might be worth my while then?

Regards removing the sensors and replacing with new, I assume it's plug-and-play from an electrical point-of-view as long as they're 433MHz?

I assume I have to deflate each tyre in turn then and somehow pry the tyre back on the wheel where the valve is to get at the sensor on the inside of the wheel? Thought this would need a tyre shop - I only have have fairly basic tools...