Motorcycle Questions? Ask a Mechanic.
Hi and thank you for your question.
Yamaha uses code 42 for 3 different problems. If you happen to know something that would make one of the options more likely, I would suggest running that one down first.
The 3 circuits that would trigger a code 42 are Speed Sensor, no normal signals received from the speed sensor to the ECM, Neutral switch, open or shorted circuit, or clutch switch, open or shorted circuit.
If you are not blowing fuses, you are probably not looking for a short, but an open. Open could be anything from a wire unplugged to a broken wire or a failed sensor.
If you need more help, let me know.
I cannot answer that for you. There are way to many variables. It depends on what is wrong with the bike. If you don't have a speed reading, and can pace yourself with traffic, that is not too terribly difficult . If the neutral light either isn't coming on or stays on, and you have enough experience to be able to test for neutral without depending on the light, then you would be safe to ride it. The clutch switch either wouldn't let it start in gear or it would start no matter what, in gear, side stand down, etc. The difference is whether it is shorted or open. It would give opposite results. The biggest variable is you. What is your level of riding experience? Have you been riding for years, and save the dangerous macho garbage, have you mastered the controls of a motorcycle and can react to emergency situations without losing control of your motorcycle? If it starts and runs, you can ride it slowly in a safe area to see if you have a speedo read out. If you do, you can eliminate that from the list. If the neutral light is acting normal, lights up in neutral and goes out in gear, you can eliminate that. Inspect the wires that are supposed to plug in to the clutch switch. it is on the bottom of the bracket the clutch lever is attached to.