It’s a common observation among car enthusiasts and professionals using a Diagnosis Plug Car, or OBDII scanner, that readings can sometimes be puzzling. Take, for instance, the throttle position percentage displayed by these devices. You might expect a straightforward 0-100% scale, with 100% representing fully open throttle. However, real-world experiences often show discrepancies when compared to manufacturer-specific diagnostic tools.
One user noted that their diagnosis plug car reached a maximum of 78% throttle on a Peugeot 206, while the Peugeot’s dedicated DIAG2000 tool indicated nearly 100% on the same vehicle. This isn’t an isolated incident. As highlighted in resources like a 4x4wire.com article concerning OBDII ECU interpretation, the scaling of “percentage type” values isn’t universally standardized across all vehicle manufacturers for generic OBDII scanners.
This means that what your diagnosis plug car reports as a percentage, such as throttle position or engine load, might not be an absolute, universally comparable figure. The data accessible through the standard OBDII protocol is often a normalized representation. For throttle position, this could be a numeric conversion of the potentiometer voltage, where 100% might correspond to a specific voltage like 5V, and 80% to 4V, and so on, scaled within a 0-255 data range.
While a diagnosis plug car provides valuable generic data, it’s crucial to understand these potential scaling differences. Manufacturer-specific tools often access more detailed and absolute data through proprietary protocols, offering a potentially more accurate picture of parameters like throttle opening. Therefore, when interpreting percentage-based readings from your diagnosis plug car, especially throttle position, consider that it may represent a relative value within a standardized OBDII framework rather than a direct, absolute percentage in the manufacturer’s internal system.
