On my 04 XKR I'm getting a P0171 Fault Code (Fuel Trim too lean, Bank 1). What does this mean and what do I need to check?

 

Most likely an air leak in the intake duct from the filter to the throttle body. Have you changed the filter or disturbed the cover? Also look for a split in the 'accordion' section of the duct. It sits over the exhaust manifold and failure is common and very hard to see without removing the duct for inspection.

The fact that it appears as a single code rather the more normal pairs may mean that it is a very marginal leak.

 

Although I'd also suspect the 'accordion' first, having taken note of the code, I'd be tempted to clear it and see if it resets before digging too deeply into looking for a fix. The possible causes are:

1. Engine misfire
2. Air intake leak between MAF Sensor and cylinder head
3. Fuel filter / system restriction
4. Fuel injector restriction
5. IP Sensor fault (low fuel pressure)
6. Low fuel pump output
7. HO2 Sensor(s) (1/1, 1/2) harness wiring condition fault
8. EFT Sensor fault (low fuel temperature)
9. MAF Sensor fault (low intake air flow)
10. Exhaust leak (before catalyst)
11. ECM receiving incorrect signal from one or more of the following components:
ECT Sensor, MAF Sensor, IAT Sensor, IP Sensor, EFT Sensor, TP Sensor

Given that two of the default actions for this code are Bank 1 closed loop fuel metering is inhibited and maximum engine speed is reduced, it could be transient if you noticed no drop in performance.

Graham

 

unless Bank 2 is directly behind Bank 1 with triggering the lean code also (you won't know unless you check the live long term fuel trim via an OBD scanner), a bank 1 only means there is a vacuum leak directly on bank 1. Unfortunately, that leaves only a couple options, the PCV valve attached to it, fuel injectors sticking out of the inlet manifold, and gaskets themselves on that bank.

First, I'd check to see if bank 2 is also showing relatively LTFT, and if so, look for more 'common' air sources, such as the throttle body, inlet elbow (below the TB) and all those connecting hoses leading to the TB.

 

Thank you for all the info. The Fault cleared itself and has not come back. Hopefully it was a glitch in the Systems otherwise there seems to be a lot of possible causes to hunt down. I'm new to working on Computerized Car but I program Machinery as part of my Job. I know there is software out there with which I can access the ECU directly through my Laptop. Is this a good thing for me to have? What is you Guys input on this? Have a great Day!

 

You are lucky that the fault disapeared.
I am a little bite desapointed with auto tests embeded into modern cars. I have a S type V8 4.0 that does not work and do no report a fault and I have a Golf VW that report a lot of DTC faults and work properly.....

 

I use AutoEnginuity with the Jaguar add on (flash drive) on my laptop. This was over $400 when I bought it last year, but I have probably saved almost that much, not to mention the convenience of having it at home. It can do a lot more than read/ erase codes, but I haven't taken the time to get into it that much yet.

 

Have you got a mode06 page in your software?
If yes, I would be interested by knowing whare are the tests supported by this mode. With my soft, they are lot that are Jaguar specific and because not described in the international standard, not supported by my soft, even if the data are reported but without any information on the data measured.
Thanks,

 

I will take a look, but as mentioned, I have not taken the time to investigate what's available. At this time I don't even know what mode 6 is. Hopefully someone with more experience will see your post and respond before I can figure it out.

 

here ya go, from an old test I ran.

 

0171 has come up a few times since I bought the car last summer. It always appears with some other left bank code (always the same one, I just forget which), and then they both reset on their own. Some folks have suggested that I replace my 110,000 mile old O2 sensors (and I should), but I honestly believe the recurring codes have something to do with the gas I fuel-up with. I usually use 93 octane Shell, Sunoco, and WAWA (local discount fuel) with few problems. Just yesterday on a road trip I tanked up with Valero (they are entirely U.S. owned and operated) on a road trip, and poof(!), within 20 miles the Check Engine came on. Haven't check it out yet, but I pretty sure I've got 0171 in there someplace, and after I refuel the next time it'll reset. We'll see.

Good luck!

 

Matt, you probably replied to my post https://www.jaguarforums.com/forum/s...-failed-87839/

The sw tool I use do not provide the detail that your does. I need to compare your plot with my records. I am affraid that the adress span of the list you provided stop at TID=22 (hex means 18 in decimal) when I am looking fo 53 (dec = 35 Hexadecimal).....
I will see.
Thanks,