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Hey Everyone, I purchased a used LR Disco 2 (2004) that looks great and ran well when I first got it. I took it into a mechanic for a diagnostic to try to determine if there was anything I should be aware of / fix preventatively and didn't find anything major. Drove it for a few weeks and eureka, started getting a P0305 cylinder misfire and the SES light came on (not blinking). Took it in since it appeared after they did the diagnostic and they couldn't find anything - they did a smoke test on everything and gaskets are fine. Cleared the code and it was driving fine.

A week later driving on the highway noticed the SES was back on, this time for a P0300 multi misfire, within the next 15 minutes of highway driving I started actually noticing the engine running hard, and the SES would flash temporarily then go back to not flashing. I drove it straight to the mechanic where they replaced an O2 sensor pro bono (since they should've caught it the first time), when I picked it up the SES was off, engine sounded good, and drove normally - also the engine temp which had been running a little hot was down in the normal range. Today I drove it on the highway and again the SES came on, same P0300 code and did flash once temporarily - I didn't notice misfires while driving, but I did at idle. Also saw a P1300 code but that seemed unrelated...

I did notice that the wire to the O2 sensor had electrical tape on it so next thing I was planning on checking was that but wanted to see if there was something obvious I'm missing.

Other details:
  • V8
  • 98k miles
  • New radiator and plugs (prev. owner)
  • I did some recent repaires: master cylinder, power steering pump, ball joints, nothing that should impact this.
 

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If the tape hides a splice on the O2 sensor that could be a problem. The D2 is especially sensitive to cheap O2 sensors, some of which do not come with connectors but need to be spliced in. You might take a look at that.

When you say it ran a bit hot, I am assuming that you have a third party temp sensor. That is because the stock gauge does not click up bit by bit as the temp increases. Instead it moves from normal to Red in one movement and that is often after the engine is overheated and you have possibly blown a head gasket.
 

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Drives like an old man
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445 Posts
Right. Probably the first thing a new Disco owner should buy is some sort of aftermarket temperature gauge. Once the dash gauge indicates hot, it's too late.
 

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2002 Land Rover Discovery 2
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198 Posts
I feel that misfires have traditionally been spark plugs, wires, and/or coil packs. I changed wires and plugs on mine and it solved all the misfire issues.
 
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