But it is so simple!
- If you connect (two) resistors serially, their resistance will add up together. Lets say connecting 2x68R together, it will be the same as using a single 136R.
- If you connect (two) resistors paralelly, their resistance will divide. Lets say connecting 2x68R paralelly, it will be same as using a single 34R.
The aim here is to get something (really anything!) which has 30Ohms resistance and can handle some load (dissipate heat).
The most accurate (from the link above) would be to use 11 pieces of 3W 330R connected paralelly. That would yield 33W 30Ohms, but i guess it would take up lots of space (11 resistors).
I also would suggest using 7 pieces of 7W 220R connected paralelly. That would yield 49W 31.42 Ohms.
Both solution is close to the resistance of the original N249 valve.
Using 3x 10W 100R connected paralelly may also work, as it would be equal to 30W 33.3R, but it is already 11% higher than 30Ohms, i don't know if ECU would report that as a faulty N249 valve.
You should have mentioned these resistors earlier, i'd have prepared and sent you one.