Hi all, I'm new to the forum so I hope I'm doing this right. I recently purchased a 2003 XKR (4.2L) and on a recent highway trip the engine light came on with the words 'performance restricted'. I took the jag in to the dealer and the following trouble codes were recorded:


P0171 system too lean bank one
P1582 electronic throttle, monitor data


The service agents weren't quite sure what these were, cleared the fault and the car returned to normal performance. I haven't taken a long drive in her yet, but around town at least the fault hasn't reappeared.


Is anyone able to shed some light for me on what these faults mean, whether they are likely to appear, and if so what needs to be fixed / replaced to solve the problem?


Thanks in anticipation, Graham

 

You can get the workshop manual JTIS, free download, for codes as well as everything else. Think about a cheap OBD tool with live data (elm327 about $10) and look at fuel trims. If bad they'll destroy the cats and can throw lean codes. Ignore other code till more diagnosis done.

 

Thanks for such a quick response. I'm not that mechanically minded, can you please advise what fuel trims are and how difficult are they to adjust/change - i.e. would it take a mechanic 10 mins, an hour etc?

 

I'm no expert but have a look at:-
What are fuel trims all about?
for a general introduction to the subject.

 

Hi Graham,

The short answer is that the 'Fuel Trim' is data output from the engine ECU and is used for diagnostic purposes. It relates to the fuel / air ratio during combustion. The ECU will always try to adjust the fuel / air ratio by adding or removing fuel from the combustion process according to various factors, but it is always looking to maintain the optimum ratio which is called stoichiometric and it equates to a ratio of about 14.7:1 if my memory serves me right.
The fuel trim data is very useful as it tells the technician, in percentage terms how much extra or less fuel is being added to the system over both long term and short term periods. If excessive percentages are displayed, then this would indicate potential problems, such as air leaks etc.

There is a lot of info on the forum about this if you want to delve deeper.

I hope this helps and I'm sure I will be corrected by more knowledgeable members if I have got any of this wrong.

Andy

 

Graham, It's worth while to check fuse # 12 (Intercooler water pump). This is located in the engine compartment on passenger side against firewall. I didn't get any codes but discovered I had a faulty I/C coolant pump when it went into restricted performance. Might double check to see if it's that same fuse # on your model.

 

Thanks for that. I'll have a look at those as well. Hopefully it has self corrected?

 

This should help you with your codes

Link http://www.jagrepair.com/DTCforms/X1...C_OBDII_R1.pdf

 

Thanks Gus, I have printed the document off. It looks excellent and will be of a great help. Thanks again!