Understanding your Subaru’s Continuously Variable Transmission (CVT) fluid temperature is crucial for maintaining optimal performance and longevity. For Subaru owners looking to monitor this vital metric, OBD2 PIDs (Parameter IDs) offer a direct line of sight into your vehicle’s data. However, deciphering these PIDs, especially when hexadecimal conversions are involved, can be a source of confusion. Let’s delve into a discussion about calculating Subaru CVT temperature using OBD2 PIDs and address some common challenges.
One Subaru enthusiast encountered a perplexing issue while trying to set up a custom PID in Torque Pro, a popular OBD2 app. The goal was to read the CVT fluid temperature, but the correct formula and offset were unclear. The process involved converting hexadecimal data received from the OBD2 port into a human-readable Celsius temperature.
Initially, the user extracted a hexadecimal value, “38,” using a standard scientific calculator in hexadecimal mode.
Converting “38” from hexadecimal to decimal resulted in “56”.
However, using an online hexadecimal-decimal converter yielded a slightly different decimal value, “58,” for the same hexadecimal input.
This discrepancy raised questions about the correct offset to use in the formula for converting the raw OBD2 reading to Celsius. The formula being tested was A*(9/5)-X, where ‘A’ is the raw PID value and ‘X’ is the offset. The user was experimenting with both -56 and -58 as potential offset values and planned to test the formula A*(9/5)-56 to see if it provided accurate CVT temperature readings.
The challenge extends beyond just the offset value. Finding the correct PID itself for Subaru CVT temperature has proven difficult. While information from other car brands, like Volkswagen, has been shared regarding PID equations and setups, the specific communication protocol used by Subaru, often identified by a TXD starting with “07E1,” might differ. This suggests that generic PIDs or formulas might not directly translate to Subaru vehicles.
The quest for the correct Subaru OBD2 PID for CVT temperature monitoring continues. Further investigation and testing are needed to pinpoint the precise PID and conversion formula that will accurately display this crucial data for Subaru owners.
