P0444 fault code

The Oily Bits S2 Specific Topics
1

Hi Guys,

Has anyone seen a P0444 fault code pop up before??

P0444 Evaporative Emission System Purge Control Valve Circuit Open

Cut and paste from the Lotus Service manual

Description

During an Evaporative Emission System Leak Detection check, the vacuum in the system is monitored by ECU
using the fuel tank pressure sensor. At the appropriate time, the test starts with the ECU closing the canister
closure value and opening the purge solenoid with the appropriate duty cycle. This allows the engine to draw
a vacuum on the entire evaporative emission system. After a calibrated vacuum level is achieved the purge
solenoid is closed, sealing the system. A leak is detected by monitoring any decrease in vacuum level over a
calibrated period of time.

This code can be caused by the purge value being either stuck closed or open.

Purge valve stuck open
A purge valve that is unable to seal correctly will result in a tank evacuation during the sealing phase of the
leak check sequence. In this phase, a pressure rise would normally be expected but when the purge valve
is not sealing this causes depression in the tank. When the pressure is below -1.7mbar a purge valve fault is
detected.

Purge valve stuck closed
A purge valve that is unable to open will not be able to achieve the required depression during the evacuation
phase. A positive pressure rise during the leak check evacuation phase will be detected. Additional purge checks
will set a purge valve fault code.

The slightly weird thing according to John is that the fuel tank pressure sensor isn�t used in European cars.

2

Don’t you get this error if the charcoal canister is removed? Have you had a hunt on Lotustalk?

3

To be fair the charcoal canister connections are going to be the first thing I look at.

4

Lol it’ll be the first thing I remove soon :smiley:

5

Can’t be dealing with dodgy fault codes man.

6

reset + forget :wink:

7

As soon as I reset it though John, it just pops back up again.

Will this code put the car into limp home John, or can I just forget about it, if I cant sort it?

8

I presume that question is aimed at JSR john ?
Not JFK john !

9

no, its aimed at you, “JFK John”

10

From what I can gather from the manual a steady mil light shouldn’t put the car in limp home and in my experience doesn’t do so …
If the mil light is flashing however then we are advised to stop the car as a misfire has been detected ( never had this happen ) if the mil light stops flashing again then the manual says drive albeit with caution !
I’ve never felt any limp home effects apart from retarded ignition after sitting in traffic.

The manual also says “in order to minimise emissions and potential engine damage,various operational limitations may automatically be applied”

11

Never had limp mode either and my MIL light was on for 2 years!

I am however interested in getting rid of the charcoal canister, is it easy? anyone done it yet?

12

[quote=ade]Never had limp mode either and my MIL light was on for 2 years!

I am however interested in getting rid of the charcoal canister, is it easy? anyone done it yet? [/quote]
I have removed the charcoal canister, but I left the electronic valve connected (Just removed it from its mounting clip on the canister) Did that as I assumed it would bring the MIL light on if left disconnected.
In the pipe work there is a nice rollover valve that you leave in the pipe;ine to stop fuel spill if the worst should happen.
I then just extended the pipework, job done…

13

might look into it a bit more, was it heavy? I know the USA spec cars ones are but their system is different.

14

Gotta laugh really cos with any other car a mil light is something that needs sorting but with a Lotus I get more concerned if I don’t see a mil now and again …makes me think the bulbs gone !

15

MIL procedure explained

If its flashing, just keep thrashing.

If its steadies, prepare to spend some readies

:astonished:

Anyone wanna buy my car? :wink:

16

Tut, tut Ade - what about the environment :whistle: the effect could be devastating in comparison to your 300 bhp exhaust emissions :slight_smile:

17

Not really, about 0.5 kgs in total but does create a fair bit of extra space above the alternator…

18

0.5kg and it is free, might be worth more of a look :wink:
My other car is the environmentally friendly one :wink: (can you get a sticker like that?)

19

In my experience MIL steady ( not flashing) has happened when the filters on the air intake ( induction) have been changed from standard , to something more free flowing . It is a very sensitive measurement .

MIL flashing I’ve not had experience of :wink:

20

Probably a dumb question, but what is the charcoal canister for?

In car BBQ?


Regarding the MIL light - it is very sensitive to changes of air filters, manifold etc - mine has been on for a couple of years - I just re-set it reasobaly frequently to check nothing eilse is wrong, it’s never seemed to retard power.
Not seen it flashing though…