New diagnostics may arrive tomorrow so I shall soon know the answer. In the meantime, I thought it might be fun if anyone wants to play guess the fault.

Symptoms

Start car from cold. Drive as normal. As soon as temperature gauge gets to normal operating temperature (in the middle) I get the book signal. Turn car off and back on, book symbol goes away.

Leave the car an hour while you go shopping, drive away but when gets back up to temperature, no book symbol.

Leave the car to cool down for a couple of hours, drive away and when gets back up to temperature, book symbol comes on.

No other symptoms at all. Nothing makes noise, runs rough or anything. Happens with hevac fans on or off and heating appears to work as it should. Blows hot and cold where you ask it to.

Any ideas what it might be?

Lazy blendmotor. If I recall correctly what Gilbertd once told me, when a blendmotor responds too slowly at the desired temperature (or in this case the different coolant temperatures to adjust the flap accordingly) the HEVAC gets a time out and flags the book.

And that would happen even with the fans turned off?

Coolant temperature sensor would be my bet. The one on the supply pipe to the heater matrix, nothing to do with the engine.

I can't remember if there is logic that expects it to see at least a certain temperature after a period of time, but it rings a bell.

Is that the pipe inside the dash on the left of the drivers footwell?

Doesn't matter how long it takes the car to warm up. Cold days longer, warm days shorter. Book only comes on when temperature gauge gets bang centre.

Yep - there should be a sensor clipped to one of them. If its fallen off, then reattach with a cable tie if the clip is broken. If its still attached but faulty, it'll show up on diagnostics as logging a fault (and probably giving a weird value).

Ok. I think I've read that if it's bust, you van just put a new sensor somewhere else on the pipe that's a bit more accessible. Is that right or is it an easy one to reach?

It's quite easy to reach. It's the one with a blue plug.

instead of guessing, and changing parts that may or may not be broken... why not ask the unit why its brought the light on?

I assume that his intention going by his first post - but until he has the means to do so, why not have a guess? We're going to know definitively soon, I'm sure he'll wait till then!

Depending on what sort of diagnostics BSM has chosen, of course. Generics are unlikely to read HEVAC faults!

Good point.

I'd go one step further and say generics definitely won't read HEVAC faults. My guess would be a lazy blend motor though.

We are, eventually, going to meet up and put my nanocom on his P38 but until the moon, stars and several planet align (or we get to the end of the events season at work and I have some weekends to myself again) I think is a long way off.

And the results are in!

HEVAC:
NANOCOM - HEVAC.APP - VALEO HEVAC fault file

(2) THE HEATED FRONT SCREEN SHORT CIRCUIT TO GROUND.

(FAULT TYPE = CURRENT)

(8) THE LEFT HAND BLEND MOTOR IS SHORT CIRCUIT TO GROUND.

(FAULT TYPE = CURRENT)

(26) RIGHT HAND BLOWER MOTOR HIGH SIDE OF REGULATION CIRCUIT FAULT.

(FAULT TYPE = CURRENT)

(30) LEFT HAND BLOWER MOTOR HIGH SIDE OF REGULATION CIRCUIT FAULT.

(FAULT TYPE = CURRENT)

(50) HEATER CORE TEMPERATURE SENSOR CIRCUIT SHORT TO GROUND.

(FAULT TYPE = CURRENT)

(51) SOLAR SENSOR FAULT.

(FAULT TYPE = CURRENT)

MOTRONIC (Cleared, did not come back)
NANOCOM - MOTRP38.APP - MOTRONIC fault file

P0172 = MIXTURE ADAPTION FACTOR FRA
BANK 1 DRIVE CYCLE C
OCCURED 25 TIMES
SIGNAL TOO HIGH
FAULT IS NOT CURRENTLY PRESENT
FAULT DETERMINED AS INTERMITTENT
FAULT CAUSES THE MIL LAMP
ACTIVATION

P0175 = MIXTURE ADAPTION FACTOR
FRA BANK 2 DRIVE CYCLE C
OCCURED 2 TIMES
SIGNAL TOO HIGH
FAULT IS NOT CURRENTLY PRESENT
FAULT DETERMINED AS INTERMITTENT
FAULT DOES NOT CAUSE THE
MIL LAMP ACTIVATION

Bonus fault:
NANOCOM - SPS2.APP - DISCOII SRS fault file

CODE 008
THE DRIVERS AIRBAG MEASURES OPEN
CIRCUIT

(INTERMITTENT)

Last one is easy, give the connectors under the drivers seat and under the knee panel a squirt of contact cleaner (worked on the Ascot).

The engine ones are probably due to the odd running before and shouldn't come back now it's running right.

HEVAC ones are weird, for there to be that many current faults suggests something very odd. When I first got my white one, I had odd intermittent faults with the HEVAC that turned out to be dirty contacts in the multiway connectors. Again, contact cleaner sorted them. I've been playing with the HEVAC and blend motors on the Ascot tonight. I'm not sure the faults reported by the Nano are strictly correct. On the Ascot, Nanocom is reporting RH blend motor feedback short circuit but testing it with a meter on the leads show no short circuit but what it does have is a short circuit motor (3 Ohms compared to 40-50 Ohms on the other two) on the LH blend motor. I checked the inputs and when the RH temperature was changed and the feedback could be seen moving but the LH one doesn't (because the motor isn't moving as the HEVAC has detected a short circuit motor and doesn't try to move it). Same goes for the blowers, you can manually adjust the speed and watch what the feedback does.

But that's probably too late now as you and the car have scuttled off in opposite directions.....

The HEVAC is horrible for throwing up random faults.

The best course of action for determining what is actually faulting in the HEVAC unit to start by ignoring whatever it has logged. Hit clear faults, and then when it says 'faults cleared' exit out of the HEVAC, turn ignition off, then back on again, and then go back in and read the HEVAC faults again.

The HEVAC doesn't actually erase the faults until it is next powered up. Usually then when you've cleared faults and powered off/on, and read again, anything that is left is an actual fault (and if it's something like the blend motor/feedback pot, you can see it (or not see it doing anything) in the live data.

The motronic faults are showing as not currently present - so again could just be logged. I've had those faults come up on mine, and usually when the fuel trims are way out, or hit the limit of their adaptation. If he's had dodgy fuel injectors, and LPG system which has been out of calibration, then between them it's probably thrown the fuel trims out, and caused those codes.

In theory I would again clear them, reset adaptive values and then see if they come back after a bit of driving. Since the injectors have been sorted, and LPGC has done the LPG calibration, its most likely the fuel trims have re-adapted to where they should be - which is why the faults are only showing as logged.

As Gilbertd says about the airbags... and the bonus with it being an '00 is it will automatically clear when the problem is sorted :)

Thanks very much Morat.

The heated windscreen I knew about. Only works half way across. Clears the passenger side lovely but the drivers side has a cataract.

I wasn't aware of any blend motor faults. I thought it all appeared to work as it should. I'll scrutinize this.

The Heater temperature core is the one I think kept chucking the book symbol up. Comes on exactly as car gets up to temperature but if you switch car off and on again, no book. Book wont come on again until you've let car cool down right down and then get back up to temperature again. Is the heater core sensor the one under the dash on the pipe???
I'll have a look at connectors for airbag as Gilbert says. Airbag light has never come on though. As Morat said, just don't crash if it comes on. lol

Since I fixed my leaky injectors, I did my own lpg calibration. I had a couple of issues to begin with with P0174, P0172 and P0175 but I thought that they would clear once my LPG was running right, which I think it now is. So as Marty says, they are just logged.

Most times if only half the screen is working, it's the earth come off, pop off the cover under the screen and get the soldering iron on it, saves buying a new screen and change plenum sponge while your there. Easy fix 😁

The two connectors for the airbags are both in yellow shielding so easy to identify. The one under the seat is to the side airbag in the seat but the one under the dash feeds the one in the steering wheel. If you drop the panel under the steering column off, you'll see it running along a bracing strut with a connector partway along. As long as the ignition is off when you disconnect them and stays off while they are disconnected, you won't get a fault. Just pull them apart and give a good squirt with the contact cleaner.