I've been getting a check engine light with a P1492 code (Downstream Throttle Air Leak) on my 2007 Mini Cooper S (R56 with N14 engine). I can clear the code but it comes back about a week later. There is a hissing sound coming from the left rear side (on the left when facing the engine, it's on the right side of the car from the driver's position) of the cylinder head cover after I shut the engine off. The hissing lasts for about 20 seconds and as it slows down, it "burps" and goes for another couple of seconds before stopping. The car is not running as well as it used to. I'm assuming this hissing sound is not "normal". I took the cylinder head cover off but could not see anything apparent but I really didn't know what I was looking for. The hissing seems to come from the back side of the cover next to a hose that connects on that back corner.
I wanted to check with the experts on the forum before I spring $300 for a new cylinder head cover - is there anything that can be done to fix the cover or is replacement my only option? Thanks for any advice.

 

Yo Projectman, whatever became of the hissing noise. My 2010 is doing the same thing, thnx

 

Really sorry to hear that - sounds like you are out some money. You will need to replace the valve cover and the valve cover gasket. The cover made out of some kind of special high-tech plastic (but not high-tech enough as it appears to be a common failure with the S). It is not repairable and has a bunch of internal baffles and spacers that are not accessible.
I would recommend buying one on-line. Warning: be prepared for sticker shock! It's not difficult to do the replacement - there are some how-to videos on uTube. The only tricky part was the hose on the left rear. You might want to consider painting the new one or getting it powder coated before you install it. You will have to peal the Mini labels off the old one if you want to put them on the new one as it does not come with the labels. Let me know if you have any other questions. Good luck.

 

Thnx for the reply. That confirms what I've been reading elsewhere. I removed the intake manifold and throttle, checked my hoses, replaced gaskets but still the same noise and throttle response loss. This is my toy so I wanna learn/fix as much as I can. Location of the noise and it being the valve cover doesn't seem to jive but I'll go for it. Found one for $309. Thnx again

 

Thanks ProjectMan! Found the cover on Amazon for $320. Easy to replace. No more hissing noise and we're back to a punchy throttle. Nice to have my car back.