I recently get these two codes. I found that the spark need to be changed, so I changed it. Then the p0171 code is gone, but the p0174 still on. I check the engine there is no vaccum leak and mass air flow sensor should be tested. Please some body help me to figure out the problem. By the way I found out that in dash the outside temperature shows wrong.

 

By the way the M.A.F sensor is ok.

 

It's not likely related to that air temp sensor but it's cheap and easy to replace. Worth getting the workshop manual $6 ebay but it's right at the front of the car about where the license plate is / would be. Covered here before so a search (but the $6 is a bargain).

How did you check for leaks? Even a small one is enough.

How do you know the MAF is OK?

Are the O2 sensors working? What are the fuel trims? A $30 ebay elm327 OBD lead will let you see. Covered before if you search.

 

I used the propane spray sprayed all the hose tube and elbow.NO leak. Mass air flow sensor also been tested. the O2 sensor also checked using OBD 2. but the long term fuel trim is around 40.

 

Go to my page http://www.gusglikas.com/AutoRepairTroubleShooting.htm and select P0171 P0174 and see if that helps. Brian and I have been working on this project and this was one of the codes.

 

Thanks

 

more than likely the lower breather elbow large tube under the injection manifold. You cant see it. What are you using that gives 40 on long term fuel trim? 20% is maxed. And that a BIG vacuum leak, like that elbow. I just change that, imt oring, upper/lower intake gaskets, and the other rubber elbow, and rubber connector on the other end of the elbow saturday for the same issue

 

Some people had taken look my car. they said, the car idling is normal and engine no shaking. Does this mean the car is not surfuring big leak?

 

Everything, including that fuel trim, says you have an air leak. I'd back Brutal's diagnosis

All those things have been covered before, many with photos and/or step-by-step procedures, so if you're interested do some searching.

 

Ive been reading alot of posts and they have really helped me. I have a jaguar s type 2002, and i kept getting the codes p0174 and p0171 i have already replaced spark plugs , i had a catalyst replaced bank 2 an also replaced the 02 sensor bank 2 upstream . I still have the code p0174 and the p0171 already removed by itself, i did not see any air leaks only on the intake manifold i could hear air coming out could this be the problem some one please reply i just need to clear this code to take my smog, they told me it was running too rich?

 

See if this information helps you understand what the codes mean and how you can locate the problem.

Link http://www.jagrepair.com/images/Auto...otos/P0171.pdf

 

Use an OBD tool with live data to see LTFTs at idle & 2500rpm to make sure what's going on. If you've the 2002 3.0 have you checked/changed the hose (under manifold; I think there's another at the engine rear) whose elbow perishes?

 

Yes i have replaced a small plastic hose that runs rite under the manifold and it has a small elbow at the end it was leaking there before but i think once i changed it the code p0171 took aff and hasnt came on. I could see one of the gaskets were the manifolds sets i just cant really feel air coming out of that section i could just hear air escaping?