Genuine Bosch fixed it, see my last post here: https://landroverforums.com/forum/di...80/#post776157

I replaced the purge valve (hyundai), got a new gas tank cap, a new leak pump (Bosch). Cleaned the tank bung, checked all lines for flow and leaks, flushed the purge line. I also checked for air leaks with a smoke test and found a small leak (intake hose did not sit tight). The code is coming back. I took the vapor canister out and an oily fluid smelling like fuel came out when I held it upside down. From what I read on the internet, the vapor canister could be damaged from overfilling and cause P0441. I tried to get the canister dry by letting it sit in the sun and pumping air through, but ordered a new vapor canister (which is still on the way). Or could a faulty the fuel pump cause P0441? I also have the symptom, that a hot engine starts slowly or sometime stalls immediately after start (crank shaft sensor was already replaced). Otherwise it runs without problems.

 

@Discorama Usually when canisters get old and fluid comes out they are dead. Had the same issue on a old R50 pathfinder, I tossed a junkyard one in and was good for years.

 

From what I learned, canisters can be damaged when you overfill and gasoline gets into it. Then the charcoal in the canister gets contaminated and can't store hydrocarbon vapors anymore. It is possible to rebuild these canisters by either replacing the charcoal or activating the old charcoal again. For now I ordered a new canister and I hope it fits (CP455) and fixes the problem. There are also used canisters on ebay, but the only way to test them is to try them out.

Another theory is that Hyundai valves do not work well. The purge valve is controlled with a 10Hz PWM signal in order to adjust the flow. I am not sure if they are made for such an application. There seem to bee differences between the valves, although they look identical and open and close properly with a DC voltage. Original Bosch (0280142308) are not too expensive either.

 

A brand new vapor canister didn't make any difference. I got the SES light within one hour of driving which means the purge flow test failed two times with the new canister already. Do new vapor canisters need to saturate for a while before they can release vapors that the ECU detects as sufficient? I could try it more times, but those tests cost money (gas).
I disconnected the electric plug from the purge valve and got a P0444 as expected. The ECU seems to drive the valve solenoid correctly.
I ordered a Bosch purge valve to replace it again. Maybe the Hyundai which I put in (not genuine, "OTUYAUTO" made in P.R.C.) doesn't work properly. The design an quality can impact the flow characteristics, since the purge valve is not operated on-off but driven by a PWM signal to control the amount of vapors released into the manifold.

 

@Discorama New tank - code should stay off

 

You mean a new gas tank?

 

@Discorama sorry vapor canister, used to call by a different name way back when teh dinosaurs still roamed

 

I measured the signal at the purge valve with a scope. Voltages are fine. The PWM signal frequency is sometimes 10, sometimes 30 Hz. Maybe the cheap Hyundai can't handle it. Waiting on the Bosch ...

 

I had an issue a few years ago with a new Hyundai valve that kept on throwing codes immediately upon installation. I switched to the Bosch and the problem went away.

 

I got a new Bosch (0280142308, genuine, "Made in Czech Rep") and that worked right out of the box. P0441 is gone and I passed the smog inspection today.



I bench tested the "Hyundai", the solenoid opens and closes the valve properly and it holds vacuum when closed. BUT. The ECU controls the purge flow gradually by actuating the solenoid by a PWM signal of up to 30Hz. The Bosch is designed for that, but the cheapo can't handle it properly. It's not worth to mess around in order to save $10 or $15 (the Bosch was $30).