Tire pressure alert

[JaviLM]

Today while driving in the Tokyo Expressway I got an alert saying that the air pressure in the rear right tire was low, and the "check engine" indicator immediately turned on too:

I got off the expressway and got the pressure checked on all four wheels at the first gas station that I found. The rear tire was indeed low, so I got it inflated to 2.3 bar. Then I hit the "Set tire pressure" button and kept driving (carefully) to my destination. When I arrived and parked the car the screen was still in the "Calibrating tire pressure, keep driving" state.

A couple hours later when I got in the car to come back home the screen says that "Tire pressure is good" and the "check engine" indicator has turned off.

For context, this is the first time I check the tire pressure in 7100 km (4400 miles), because my understanding was that the pressure sensors would give an accurate reading, but apparently they don't work in the same way here in Japan, according to a thread in the Japan forum.

How worried should I be about this?

 

[virtualmacho]

How worried should I be about this?

The TPM system functionality for the Emira are limited in Japan: they won't give you a "constant reading", only an alert when the pressure is outside predetermined thresholds. This is what you experienced. Nothing to worry about the electronics.

However, only one of your tires is low, and this what you should be worried about until you find the reason for it. It could be a loose or defective valve, a cracked wheel, puncture, etc. I just went out and checked mine, and the fronts were a hair under 2.0 bar, rears somewhere between 2.1 and 2.2 bar. Left and right sides were pretty much even. Looks pretty normal after running 1,600km since the last check and fill (part of the 6 month dealer maintenance I had in May).

 

[virtualmacho]

It's an analog car --- do it the analog way !

 

[JaviLM]

Update on this: the day after this happened I bought a tire pressure gauge at an Autobacs near home and confirmed that they were all fine, and didn't have any more issues...

...until yesterday.

Yesterday while driving in the expressway I get another emergency warning in the dashboard saying that all four wheels had low pressure:

I kept driving home, and when I arrived I checked the four wheels (while still hot). They were all fine.

I checked again this morning with cold tires and they were all mostly fine: the front left and rear right wheels were a bit on the low side, but nothing that should have triggered the TPM alert. The alarm in the dashboard had already cleared without me touching anything. After inflating them with the compressor in the repair kit I went out driving and didn't have any more issues so far.

It feels as if the TPM is giving inaccurate readings.

 

[Nick Sticks]

Ha, just realised you can use the repair kit compressor for just inflating tyres - I thought it was just for inserting the gunge!
I had bought a Michelin Programmable Inflator with Quick Release Valve after borrowing someone's simple inflator with the screw on end which I found annoying to use.

 

[virtualmacho]

Yesterday while driving in the expressway I get another emergency warning in the dashboard saying that all four wheels had low pressure:

Now you need to worry about the electronics
Sounds like a wiring harness and/or grounding issue, as the computer thinks all four transmitter/receiver pairs have failed. You may want to book some time at the dealer to have them open some panels and check the wiring...

 

[JaviLM]

Ha, just realised you can use the repair kit compressor for just inflating tyres - I thought it was just for inserting the gunge!

As long as you don't plug the cylinder that contains the gunk it works just like any other compressor. This is one of those rare occassions when I actually RTFM.