Hi All,

I recently purchased a 2004 Disco 2 with about 95k on the clock. All was well for about 2 weeks then got the 3 Amigos (luckily it was a wheel bearing). Another good week goes by, and CEL comes on. It throws a code for O2 Sensors too lean ( P0174, P1174). I take it in with new O2 sensors from Atlantic British. The shop mentioned to me "You had the upstream sensors in the downstream and visa versa". So they put the new sensors in along with a MAF sensor and it ran well (honestly the best its run for the last two months I've owned it. A couple MORE weeks go by and the CEL comes back on... At this point I don't see much of a change in drivability so honestly I ignored it until I was able to find time to drop it off.

Now here we are... May 2nd 2026 and the thing starts going wonky. I started it up one morning and as I was pulling out the CEL starts flashing (misfire, f**k). As I got up to about 35mph the vehicle starts shaking with acceleration. It turned into a CRINGE level misfire.

My O2 codes come back up again with P1174 and P0174 along with misfires in 1,2,3 cylinders and random misfire. My trusted mechanic is out for 3 weeks and I need a car. (I do daily my Disco)
I'm novice but able to do repairs and have just about every tool - just not the time. Should I look for a vacuum leak? Should I replace the plugs? Should I look at the injector O rings? Should I swap my O2's?

Please ask away and happy to take any advice.

Sam

 

https://landroverforums.com/forum/di...sfires-126863/

 

What Extinct posted is very helpful. I have been in your shoes, limited time. I would buy new plugs, and fashion a smoke test, unless you can rent one from a local autoparts shop. My thought has always been, within reason, if I am going to remove the part, i may as well put in a new one. Cylinder 1,2,3 are not common sided, so there is not a lot of direction as far as which bank. I would trace the spark plug wires, the o2 sensor wires, see if there is a short or something damaged from the work around the MAF and the O2 sensors. My hunch is the smoke test will you what is going on. If you go down the road of injector seals, may as well put new injectors in, or test yours, seems unlikely three would go out at once.

get a can of maf cleaner and electronics cleaner and hit the connections, no reason not to if you are under the hood.

 

Did you swap the MAF out with a generic one or OEM? I've had a faulty generic MAF right out of the box. Try OEM, if you haven't already.

Inspect your air/fuel/spark-related wires for shorts, to include your o2 sensor harness clips.

Check your intake tube for cracks.

I had similar issues a years ago and the problem turned out to be deteriorated fuel injector o-rings.

 

The above thoughts are good, but I wouldn't replace the injectors, unless you go with OE or OEM. I wouldn't trust the Chinese knock offs. You could get your originals tested though.