Err21
Watch below video and use a multimeter to check the accelerator voltage
(Normal voltage range:
When accelerator is in neutral position, the voltage should be 2.5V
When it is pushed forward, voltage should reduce to 0.5V
When it is pushed backward, voltage should increase to 4.8V )
Cause of failure:
1. If accelerator voltage is normal, then display circuit board is faulty
2. If accelerator voltage is abnormal, then accelerator is faulty
Tools: multimeter; allen wrench