Hi guys.

Engine Management light came on today on the way to the office. Got home and plugged it into my ELM-usb interface and tried some software I found online.

Gave me the trouble code P0458 - Evaporative Emission System Purge Control Valve Circuit Low.

Would obviously seem to indicate some sort of electrical fault in the purge control valve circuit - just wondering if anybody knows the best way to test this?

Is there a fuse for the PCV circuit that I can test with a multi-meter? The PCV itself is housed beneath the battery and battery tray, and I'd rather not have to take that out and start cutting wires to test the circuit if there's a fuse or something handy.

I've cleared that code anyway, and might well be a one-off and never illuminate the engine management light, but I'd like to check just to be sure! Don't want to leave it and end up failing an MOT for emissions at some point in the future...

from what i read you cant do it youreself and even experienced technicians have problems finding and fixing the issue but it needs specialist testing equipment so unfortunately youll need to get it to a dealer

from what i read you cant do it youreself and even experienced technicians have problems finding and fixing the issue but it needs specialist testing equipment so unfortunately youll need to get it to a dealer

Surely not! From my understanding it's just a 2-wire valve? One 12v live feed, one negative feed to the ECU? Shouldn't be difficult to test with a multimeter, no?

google it from what i read its not so easy

google it from what i read its not so easy

Can barely find anything on it if I'm honest! Any helpful links?

http://www.aa1car.com/library/evap_system.htm

I see what you mean, it's obviously a complex system as a whole, and if the valve itself fails and you get leaks, they seem quite difficult to detect and repair.

But code P0458 seems just to be an electrical fault and not an actual fault with the valve.

try this it relates to a nissan but its the same system http://nissanhelp.com/diy/obd_codes/p0458_subaru.html

It's probably the solenoid itself that's playing up. I would try swapping it with another one if you can get it cheap enough

Is the car still running ok?

Yup, car is running fine - haven't noticed a difference. Wouldn't expect it to run any differently as my understanding is that this system only exists to stop evaporated petrol getting into the atmosphere. So car might well fail an MOT based on increased emissions, but wouldn't expect a dip in performance.

I'll try to source a replacement valve and see if that works. Can't find anything on eBay, only a few from america that seem to be for that mk1 or mk2 2.0L, so not entirely sure they'll fit.

I'll get myself to a breakers yard over the weekend and see if I can get one there.

Got this sorted btw. It was a stupid stupid issue.

Found an electrician who told me that very little ever goes wrong with these valves (as they're such simple devices) and usually it's just a fuse issue. He told me that F35 was the fuse I should be concerning myself with, and lo and behold that happens to be the fuse that I was piggybacking for my aftermarket DRLs... so the DRLs must just have been drawing current from the PCV circuit and giving me the code.

Changed the DRL fuse to its own fusebox slot and put the original fuse back in F35, gave the car 10 quick ignition cycles and code disappeared and hadn't returned.

Glad it wasn't an expensive problem!

Hi I have the same problem on my cmax 2005 engine management light came on checked fuse f35 in engine fuse box and its blew every time I put 10amp fuse just keeps blowing it please does ant 1 no how to sort it

I plugged it in to diagnostic it's giving me the code p0458 it only happened the other day everything is running fine just wanted to know why fuse f35 keeps blowing please does any 1 no what could be the problem