What is the V-ref value for a typical electronic diesel engine management system?

• A. Less than 1 V-DC
• B. 5 V-DC
• C. 56 V-DC
• D. 4.5 V-DC

Answer: (B)

Sensors in an electronic diesel engine management system are powered by a fixed reference voltage from the ECU, which defines the signal range they can produce. That reference is standardized at 5 V DC, providing a 0–5 V signal range for many sensors like MAP, MAF, and temperature sensors. The 5 V reference is what makes sensor outputs consistent and compatible across the system. Options that are much lower, like less than 1 V, or much higher, like 56 V, don’t fit automotive sensor practices. While some sensors can operate with slight variations, the standard and most widely used value for V-ref in this context is 5 V DC.