Vanden Plas

 

Er.... near 10 yr old thread and that's all you post - why???

Asking to be deemed a spammer....

 

Well, it is ten years later and I still don't see the definitive check A., B., C., as I usually see on this forum. I am getting the P0171 AND P0174 codes but only if I drive the car at highway speeds for about 20 miles. It sometimes goes in to "Restrictive Performance," but not often. I have also once gotten a P0456 - small evap leak once.

It is a bit of a mystery to me. If someone could offer a step by step, I would appreciated it.

 

Search on / read workshop manual on the latter code and fix it then the others may also go away but if not there are a LOT of threads detailing what to do about them.

 

I've been trying to fix this problem for a long time. Although I tried all the suggested solutions, I could not resolve them.
my car is 2007 Jaguar X - type AWD 2.5 gasoline and integrated with natural gas fuel system.
as far as i research the reasons for this failure:
1- relevant sensors (maf, 02 etc.)
2- Too little fuel
3- Too much air
changing fuel filter, sensor or intake manifold seals didnt solve it.
But the solution was in natural gas fuel system. When i deactivated the natural gas system, the problem solved. the natural gas system had to be recalibrated.

 

I have a little more info on the curious way I am getting these codes.

I drive to work abut 18 miles one way. I can reset the error codes and drive to work and NOT get a return of the Check Engine/Restricted Performance. I leave my house in the morning and it's about two miles until I get on a restricted access highway and hit speeds of 60 mph. I have a short half mile block until I hit another highway/interstate and drive the remaining 15 miles to my work at 60 mph. Again, not codes.

I work about 5 hours and then it is time to return home. A short 2 blocks until I hit the interstate and accelerate to 60 mph again. After about two miles the Check Engine light and Restricted Performance Mode show up. But I do notice ANY restriction in performance. After driving the car at 60 mph for about 6 miles, like clock work, the Restricted Performance Mode message turns off but the Check Engine Light stays on.

I read the codes when home and always the same P0171 and P0174 codes (too lean both banks).

I took all the parts of the intake tubing off, inspected, cleaned, lubricated gaskets, ether tested and replaced air filter. Still did not fix problem.

 

The Jaguar code 171/174 states
engine misfire..

Air intake leak between MAFS and throttle..(Also wiring/connector, bad sensor).

Fuel filter, system blockage

Fuel pressure regulator failure (low fuel pressure)

Low fuel pump output

HO2S harness wiring condition fault (Don't discount any of the 4 lambda sensors).

Exhaust leak before catalyst

ECM receiving incorrect signal from one or more of the following components:
ECTS, MAFS, IATS, TPS.

That's quite a list of things to check, so no wonder there isn't a definitive answer. Work through each of the suggested items until you hit gold, it's one of the very few 'tricky' to diagnose codes on these cars (AJ27).

 

Thanks Sean, I do appreciate you condensing it to that list. Can you point in any first direction since it is only happening at higher speeds?

 

Clean your throttle bore and plate; clean your MAF; run a good cleaner through your gas tank; change your fuel filter, after you have made sure you have an air tight run from the air filter box to the throttle body.

Reset the code and try again after each fix. Check back. On a supercharged Range Rover Sport with the 4.2 engine, can of Sea Foam or Gumouts best usually cleared both codes for months. Once I cleaned the MAF and throttle bore/plate, never had the problem again on last X308.

But, in the end, probably fuel pump is going out.

 

Codes received at higher speeds tend to lend to the EVAP system when the EGR and Purge valve are more readily functioned. Have you run a smoke test on it? I would seriously suspect a dried cracked o-ring or a faulty purge valve, even a bad EVAP purge canister.
The 456 is a small leak, which can sometimes be fixed by simply getting a new gas cap.

 

How about >Jaguar Souvenir< on sale somewhere in southern spain
also XJ Spot, Tipe, Souvering,
i could pull few more but that's gonna suffice for now..

 

Hi Andrew I have a 2007 Range rover sport with p1074 code. can you please email me at austinsec@gmail.com I need some help.