S-type 2003 4.2L SE. its driving me mad!!! have replaced O2 sensors, new plugs & leads, PVC valve, breather hose, MAS cleaned etc. etc. and even put the extra O ring on the dipstick but this light keeps coming on. I have noticed that when I accelerate quickly and the light is on it "kangaroo hops" but when the light is off, its all fine? I have just about had it...Please, someone out there give me a hint what to do. Cheers... Dave.

 

So what codes have you found with your reader? Throwing parts at the unknown is very expensive.

 

Could you post a link to the the "Plug leads" you installed?

 

Leads = coils????

 

Hi mate, the codes are P0171 and P0174. I have been told they signify lean mix which could mean a lot of things but since everything has recently been replaced (at great cost), I guess it might be a vacuum leak? Cheers...Dave.

 

Not sure which plug leads. I only purchased the car yesterday and all the replacements where done by the previous owner. He love this car and only sold because he is moving overseas and he tried just about everything to fix it.

 

Hi Joycesjag, not sure what you mean by Leads=coils?

 

Sorry Dave, Rick was trying to be helpful while I was being a Smart-A. Your engine is coil-on-plug, so there are no leads. However...since you claimed to have renewed "plugs and leads" I was interested in a pic of what you'd fitted. You should find 8 coils, one each mounted atop each spark plug on the cam-covers.

P0171/174 are lean codes for both banks, so you are likely looking for a vacuum leak in the intake tract somewhere upstream of where the air-path splits off to the separate banks. Much written here on it, just search using the codes.
Not always an easy find, good luck with it.

Edit: when I said, "Not...easy find" I was referring to the actual leak source, NOT threads about the lean codes....those are plentiful!

 

Most/all the parts you've replaced will not have anything to do with the codes you've found. Look for vacuum leaks as recommended. Lots of info if you do a search.

 

Hi, I just had a look at the paperwork on repairs and you are correct. It says the following: Replaced: platinum spark plugs, breather hose, PCV valve, gasket inlet manifold, oxygen sensor and cleaned MAS, and put in two dipstick O rings. Being a non-mechanic most of that means nothing to me but I know the previous owner tried at great cost to fix it. I have cleared the error codes but the light comes back on saying RESTRICTED PERFORMANCE with about 5 minutes. Any help would be greatly appreciated. Cheers... Dave

 

Follow the advice already given, especially about air leaks and using Search.

Otherwise find an expert you can afford or sell the car now.