No No No No .... the inflation PSI noted on the driver side door jamb is "cold" pressure ... regardless of whatever the ambient temperature is. So, IMHO, buy a proper tire pressure gauge and learn how to use it to ensure your tires are properly inflated. A decent reliable one is worth the few bucks ... the ones hanging on air pumps at gas stations are junk! Accugage makes very suitable and easy to use gauges - for me they are easier to use than the digital types and don't require batteries.

http://www.sears.com/shc/s/p_10153_1...u=02820529000P

And the nitrogen hype is (Again IMHO) HYPE .... but if it works for you ... go for it!!

 

I had the same thing when I bought my wintern tyres. Not sure did the mechanic set exactly same tire pressure for each tyre.. Anyway the next day when i was coming home from work it showed me that same tire pressure alert.. I checked my tires and nothing also. I just set same pressure for each tyre and resetted the RPA from Idrive.. All 3 wheels had 2.5bar and one had 2.7 bad. So the system is quite sensitive..

 

An '04 has the FTM system. Like already said, the FTM works by comparing rotational wheel speed against each other. So, if you set your tire (all) pressure to 10psi and reset the FTM system, all will be considered good and you will not get a flat tire warning.

The FTM is triggered in one (or more) tires lose pressure and thus the overall tire diameter shrinks which causes it to rotate faster than the others...bingo a warning light. The FTM system is WAY less sensitive than the TPMS system and usually requires a 10 psi loss or so to trigger the warning. you can have one tire low, reset the FTM and the system will believe all tires are fine. So, check the pressures before initializing the system.

IMHO, the FTM is way more reliable than the TPMS system and WAY less agravating. Problem is that NHTSA (or whoever) does ont allow FTM any longer...I believe all systems must now be of the TPMS type (i.e. tire pressure is individually measured and compared to a low value limit).

 

I have this happen every 2 or 3 days I just do it the old fashioned way and keep an eye on my tires myself.