Hello Roverers...

After a while without SES light lighting up, my 2002 Disco S2 SE with 235K miles is showing a P0305 code for over a week now; and it is also showing P0130, P0139 and P0159 as PENDING.
Now SES light flashes and occasionally stays solid. Disco sputters softly and you can feel it running a bit rough.
According to muffler shop visited, driver side CAT needs to be replaced -it is clearly making rattling noises for a while now.
Gas mileage has come down a bit from its usual 12-13mpg, it is now at 11-12mpg -not much, but I can see the gas needle come down much faster.
I finally serviced it yesterday myself -changed oil and filter, and the day before added a bottle of fuel system cleaner before fill-up. I had not serviced it for maybe 10K+ miles -my bad! I usually serviced it every 3.5K miles, then moved up to 5K ...but really took a hiatus this last time around. I use Rotella T4 15w-40 diesel as recommended, and Mobil 1 M1-204A filter -I also throw a bottle of Motor Medic before the oil change.
Truth be told, I do feel it less noisy and running a bit better after servicing it, but it is still not running as it used to, and need help clearing the codes, unless these are product of a bad ca, and replacing the cat should get things sorted out.
I have an ELM327 and running Torque Lite on my phone.
I'll appreciate your input, thanks.

 

Don't worry about the pending codes. Start by swapping #5 plug with a different cylinder, then do the plug wire, then the coil, then the injector. One at a time.

 

Thanks EXTINCT, I'll do the plug swap tomorrow and go from there, just confirm if I should clear the codes afterwards to see if it resurfaces ...and you're right about the pending codes, P0130 cleared since yesterday's service ...the other 2 remain, but I won't mind about them while pending.

 

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As per your suggestion, I started by swapping #5 plug with #6 ...plug pulled from #5 looks pretty nasty compared to the one pulled from #6 (see pics attached). ​


Pulled from #5


Pulled from #6

Cleared all codes before driving away and immediately SES light starts flashing and occasionally keeps steady. P0305 code immediately appears as a LOGGED fault, as well as a PENDING fault, along with P0300. Although is running much better after oil change, I can still feel a soft rough idling, and can also hear like a soft "puffing/hissing" sound that accelerates when given gas, you can listen to it in file attached. I have not heard the rattling noise that used to come from CAT.

Please advise if now I need to swap wires, or if I should give it a couple days.

Thanks.

 

Your P0305 indicates that swapping the plugs didn’t solve the problem. Next try swapping ignition wires (it’s not easy to get at the coil end of the wire, there are lots of threads on this forum about how to change ignition wires).

 

...yup, thanks HARVLR! ...from own experience I'm not too fond of going near that rear-facing coil pack in such a tight-space -although a task I'm pretty familiar with, I hate it; I'm just debating between how to approach it ...1.- if swapping #5 with # 6 wire, which means double trouble, or simply replace #5 with a similar wire that I have as a spare and know works fine ...and 2.- if to attempt reaching into that tight area to do the swap without parts removal, or if to go through the trouble of removing parts in the way in order to reach the coils more freely ...I'll give it some thought and report back when done.

Good thing is that no pending faults have resurfaced since the plug swap, and scary noises heard before quietened down or stopped ...Thanks again.

 

If you have a known good wire, I’d say go for it. Also, I’m assuming that you cleared your previous fault code with your OBD2 reader. Otherwise it’s possible that you fixed the fault but it is still logged.
Yes, it’s a debate whether to remove parts to access the coils or not.

 

...yes, I cleared the codes once I swapped the plugs, and will do so once the wire is replaced. Today feels much rougher than the days before as soon as I start it ...it calms down a bit afterwards.

 

Ah, now you know the purpose of this: https://extinctmotorsports.com/land-...elocation-kit/

 

Not to start a debate or anything but the Bosch Motronic's setup on the 99-04 D2 4.0L/4.6L uses a wasted spark setup and it requires platinum plugs. Sure Copper will work, but it's designed around using platinum plugs for longest life and best spark.

NGK BKR6E = Copper
NGK BKR6EGP = Platinum
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