Regarding sensor problems, who is correct: Technician A says a poor ground in the reference voltage circuit can cause higher readings, Technician B says small amounts of resistance will not significantly affect performance?

Regarding sensor problems, who is correct: Technician A says a poor ground in the reference voltage circuit can cause higher readings, Technician B says small amounts of resistance will not significantly affect performance?

• A. Only Technician A
• B. Only Technician B
• C. Both A and B
• D. Neither A nor B

Answer: (A)

The important idea here is how the reference voltage’s ground path affects a sensor’s readings. If the ground connection for the reference is poor, current flowing through that path creates a voltage drop. That shifts the reference level upward or adds noise, so the sensor’s output is interpreted as a higher value by the ADC than what is actually present. This is a common source of false high readings in automotive sensors, especially when the sensor circuit has any significant load or the environment is noisy. Technician A’s point is the relevant one because it directly ties ground integrity in the reference circuit to elevated readings. Even small amounts of resistance in the return path can matter, you can’t safely dismiss their impact, especially with high‑impedance sensors, varied loads, and noisy electrical environments. So the statement about small resistance not affecting performance is not generally valid. Therefore, the correct conclusion is that Technician A is correct.

The important idea here is how the reference voltage’s ground path affects a sensor’s readings. If the ground connection for the reference is poor, current flowing through that path creates a voltage drop. That shifts the reference level upward or adds noise, so the sensor’s output is interpreted as a higher value by the ADC than what is actually present. This is a common source of false high readings in automotive sensors, especially when the sensor circuit has any significant load or the environment is noisy.

Technician A’s point is the relevant one because it directly ties ground integrity in the reference circuit to elevated readings. Even small amounts of resistance in the return path can matter, you can’t safely dismiss their impact, especially with high‑impedance sensors, varied loads, and noisy electrical environments. So the statement about small resistance not affecting performance is not generally valid. Therefore, the correct conclusion is that Technician A is correct.