Land Rover Repair: O2 sensor, emission, misfiring issues with 2002 Disco II, p0171 system too lean bank 1, fuel injector cleaner


Question
Hello,

I have Disco 2000 - bought used in 2004 at 19,000 miles. Took in to dealership for 30 or 36K maintenance June '05 and have kept up with oil changes and tire rotations as scheduled. Last year had the truck in a local shop to replace clamps, hoses and gaskets, etc. chasing a mystery leak. I suspected an exhaust leak under the car, where the A/C condensate would normally be because in the morning when warming up the car, I got the same spot at the tailpipe.  I also faintly smelled coolant. The shop found that coolant had been leaking from the reservoir hose.  The very next shop visit soon after had the radiator replaced as it started leaking. So I know what it LR repairs cost and still want to keep my Disco. I am not a mechanic and don't want to be, but I would like to know more about repairs being done on my car. I am truly grateful for your website...thank you!

Current dilemma: July 25 - SES on with rough idle. Codes read at Auto Zone: P0134 O2 sensor no activity (Bank 1 Sensor 1) and P0171 System too lean (Bank 1). Took immediately to LR Dealership where they diagnosed and replaced LF O2 sensor fault and a bunch of bulbs that were out. A couple of weeks after that, coming off the highway, the engine started idling rough and the SES light came on again. We drove directly to Auto Zone and this time the codes found were P0130 Bank 1 Sensor 1 and P0171 again. The sales man recommended some fuel injector cleaner (Lucas) with half tank of gas and this seemed to remedy the problems - SES light went off after driving a few miles with the cleaner in the tank. Halfway through the NEXT tank of gas (with no additives), coming off the highway again, SES light came on, engine idling rough when  in gear and I'm getting the following codes: P0130, P0171, P1171 FAM, P1412 emissions, P0300 random misfire and P0305 cyclinder 5 misfire.

I have found a local LR specialist (finally!) and plan to take my Disco to him for work, but I wanted to find out more about what to expect repair-wise. I am not convinced that the dealership fixed my problem and I also don't want to string the problem out over multiple visits to the shop. I would rather get in there and spend the time/money in one visit to take care of problems.

If I brought the car to you (I can't though because I'm in Oklahoma!), what would you do (suggest I do/have done?) Is there something obvious that we should look at?

Thanks so much in advance,
;.)
Nols

Answer
Reading your story, I think you have more than one issue with the truck.  I also think the misfire problem is intermittent, and it's just coincidence about the injector cleaner.  I think they reset teh computer and it just took a while to fault again.

Intermittent problems can be tough to track down, since it's hard to know when the problem is fixed if it doesn't act up anyway 99% of the time.

I suggest you choose a capable repair facility, and stick with them for the several visits and hours it will take to sort this out.