The On-Board Diagnostics II (OBD2) system in your vehicle is designed to provide valuable data about its operation. For enthusiasts and professionals alike, accessing this data is crucial for diagnostics and performance monitoring. However, a key question arises when working with OBD2 systems: Is It Possible To Change Obd2 Readings, or perhaps more accurately, influence or misinterpret them?
Understanding how OBD2 data is retrieved is essential. It’s not simply a passive data stream; it involves a query-response loop. Your OBD2 scanner or monitoring tool sends requests to the vehicle’s computer, and the computer responds with the requested information. This process, while seemingly straightforward, has limitations, especially concerning the rate at which these queries are sent.
According to ELM Electronics documentation for the ELM327 chip, a common interface for OBD2 communication, the speed at which you request data matters significantly. Specifically, for vehicles using the J1850 protocol, the J1979 standard update from April 2002 highlights potential issues with rapid data requests. The documentation warns against exceeding a query rate of 10 times per second (100 milliseconds intervals). Exceeding this rate could lead to problems because sending queries too quickly might overwhelm the OBD system’s message queue.
This situation raises concerns about potential buffer overflow. Imagine trying to pour water too quickly into a glass – it spills over. Similarly, excessive queries might overload the OBD system’s capacity to process and respond, potentially leading to data corruption or even, in a worst-case scenario, damage to the OBD system or the engine computer itself. While the risk of permanent damage might be overstated, it’s a crucial point to consider: pushing the system beyond its limits can lead to unreliable readings and potential issues.
Fortunately, OBD2 monitoring tools often provide options to control the data sampling rate. For example, the obdgpslogger tool available on Ubuntu systems offers a --samplerate option. This allows users to specify the number of samples per second. The manual explicitly warns against high sampling rates for older vehicles (pre-April 2002), advising users to stay at or below 10 samples per second in such cases. Furthermore, it provides an --enable-optimisations option, which, while potentially increasing sampling speed, also carries a risk of inadvertently violating OBD2 standards if used aggressively.
Therefore, while you might not be intentionally changing the fundamental data within your OBD2 system, it is certainly possible to influence the readings you obtain. Requesting data too rapidly can lead to inaccurate or incomplete information due to system overload. To ensure reliable OBD2 readings, it’s crucial to respect the system’s limitations, especially regarding query rates. Utilizing software tools with appropriate sampling rate controls, like obdgpslogger with a conservative setting such as --samplerate 10 --enable-optimisations, is a prudent approach for accurate and safe OBD2 data acquisition. Always prioritize data integrity and the health of your vehicle’s systems over the desire for excessively fast data collection.
