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sprinkles08, ASE Certified Technician
Category: Jaguar
Satisfied Customers: 21436
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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09 XF supercharged. Has check engine on and off

Customer Question

09 XF supercharged. Has check engine on and off periodically. Forget what exact code was but was for lean bank 1 I believe. Idles up and down. I suspect a vacuum leak? The only hissing sound I hear is coming from PCV, when I press on it it changes hissing noise. Could this be the culprit?
Submitted: 5 months ago.
Category: Jaguar
Expert:  sprinkles08 replied 5 months ago.

Hello and welcome to JustAnswer!

A vacuum leak will definitely cause the engine to run lean and set a code, but low fuel pressure, an inaccurate MAF, oxygen or MAP sensor can also cause a lean code to set.

The crankcase vent valve making noise may not be an issue as it always has flow, but if you can press on it and the noise changes then there may be an issue there. It may have a leak at a plastic weld seam and you're partially sealing the leak when pressing on it.

Can you elaborate on exactly how you're pressing on it?

Customer: replied 5 months ago.
Just pressing lightly on the top of it (round part) and the pitch of the hissing noise changes.
Expert:  sprinkles08 replied 5 months ago.

Do you have some carb cleaner? You can spray it to see if the noise changes or if it alters the idle. If it alters the way the engine runs then it's leaking for sure.

Customer: replied 5 months ago.
I will get some and try that. Thanks
Expert:  sprinkles08 replied 5 months ago.

You're welcome!