I have an '03 Discovery II. I have never had any real problems with the truck. The guy I bought it from had a lot of stuff done prior to my purchase. I replaced the front drive shaft after I had a loud vibration issue and I found on this forum that it was a must to replace it. I replaced it and it was all better. So I am coming back to the forum for more help.
My Throttle body heater sprung a leak, which from my understanding is pretty common. I ordered the parts and while I waited I put in two new rear O2 sensors. The service engine light would come on every now and then and I couldn't drive the truck while I waited for the parts so I went ahead and put the new ones I already had in. I also did an oil change while I had the time.

I put in the new TBH and O2 sensors and put everything back together. I took it out for the first drive after the repair and the truck was fine at first then ran sluggish and for the first time ever the SES light was blinking. It worried me so I took it to my local auto part store and had the codes read. It had multiple misfire codes. I had never had any problem with the way the truck ran before so I am curious if there is some correlation.

I am not sure with the amount of coolant that sprayed the engine if perhaps the plugs and wires just got soaked and they need replaced?? I figure if it was a head gasket or coil pack I would have saw some type of sign before replacing the throttle body heater....???

 

Please post the code numbers, not the text that the code reader "thinks" go with the codes. You can also look up the numbers in the RAVE shop manual or Bosch ECU manual (both downloads below).

Bypass of throttle body heater line should not make codes. But coolant into connectors for O2 sensors can. Also, if you used who-knowz-dey-might-fit O2 sensors that can be a problem. When it is dark tonite watch under hood at idle for any spark lights from arc overs around wire, coils, plug boots, etc.

SES flashing is usually a code that indicates misfires at a CAT damaging level.

 

I used O2's from Atlantic British.

the codes are

P1412
P0300
P0430
P0134
P0305
P0303
P0307
P0301

Thank you for any help!

 

well it ended up being that all the spark plugs were pretty shot. The cylinders that were misfiring had spark plugs that were charcoal white. I put 8 new +4 plugs in and it ran great. The O2 sensor code came back and it runs rough from time to time. I am about to replace the O2 and should be good as new.

 

New to the Rover world. Just got myself a 96 Discovery with 178k miles, starts and runs decent, however SES light on and blinking... Found this thread helpful
I am gonna attempt spark plug change with new plug wires this next weekend
What spark plugs are recommended ? What Wires should i go with

I have heard Champion copper core plugs and good for this 4.0L application
Also heard 8mm wires are good combo, what brand ???

My Pass-side Cat sounds rather lound, assuming it is damaged and also needs replacing, and I imaging the O2 sensors will be around the same time

Fun project