An engine adopts electronically controlled high pressure common rail injection technology, the SOFIM8142 Nanjing Iveco NJ2046 teaching vehicle. The fault is a slight jitter and a similar "knock" sound when the engine starts running. The acceleration is more obvious, and the engine speed can not be improved (less than 2000r/min). The fault indicator of the cab dashboard fault shows that there is a failure. Fault check: