Check eng. lite came on, read codes and got 171 (lean bank 1) How do I correct this? Jaguar is 2000 XK8 4.0 w/57,000 mi.

 

Google the error code, it gives you many links back to this very site for the issue and the fixes. Prob have a vac leak or the like somewhere

 

Hi.

Here you go.
Start with simplest first.
Check for an air leak, especially at the "accordion" part of the intake.
Clean MAF sensor with mafsensor cleaner, nothing else.

 

The P0171 is for "A" bank and not both banks so for now I would not be looking for a leak. I am thinking you are having a problem with fuel presentation on "A" bank. Get yourself a can of BG44k and add it to your fuel and see what takes place. Your problem could be something other than this but for now try this. You can get BG44k at most dealerships or auto repair shops. Give this a try first.

Gus
www.jagrepair.com

 

+1 on Gus's assessment - a leak would tend to throw a rich code if anything. Being on one side reduces the chance of it being the MAF or fuel filter, so it's likely a fuel problem at the injectors.

 

An air leak causes lean codes, not rich ones, but usually both banks.

 

<facepalm>. my apologies; a leak will cause the engine to run richer (with higher fuel trims)

 

Sorry to be pedantic but it tries NOT to run richer or leaner. It tries to add fuel to compensate for the unmetered air to get back to the proper mixture. But yes it will overall tend to run rich since it will add too much rather than too little extra fuel because running lean destroys engines whereas too rich "only" destroys cats, which are cheaper. Ideally it would exactly compensate but leaks aren't so helpful as to be consistent!!

 

no need to apologise, that's a good clear explanation which helped me.
The added fuel doesn't mean it is running rich, another c*ckup on my part!

 

clean or swap out your MAF sensor, if you're sure you don't have a vacum leak