The Brief
A pair of R35 GT-Rs came in together, both experiencing intermittent gear selection issues. The drivetrain warning light would trigger occasionally but wouldn’t always stay on, the kind of fault that’s easy to ignore until it gets worse. Both owners wanted the issue properly diagnosed and resolved before it escalated into something more serious.
The Build
This is a common issue on earlier-model R35s. The GR6 dual-clutch transmission relies on a network of pressure sensors and solenoids to manage gear engagement, clutch actuation, and line pressure. Over time, particularly on pre-2012 models, these sensors can drift out of spec or the solenoids can develop intermittent faults, leading to hesitant shifts, missed gears, or the drivetrain warning appearing under load.
Rather than throwing parts at it, we ran full transmission diagnostics on both cars, logging live TCM data across multiple drive cycles to capture the intermittent faults. Static fault codes alone don’t tell the full story with this kind of issue, you need to catch it in the act. We monitored solenoid response times and cross-referenced pressure readings against known-good values, then isolated the root cause to pressure sensor drift and solenoid response issues in the mechatronic unit. The affected components were replaced and the transmission was re-adapted to ensure correct clutch engagement points and shift calibration. Post-repair, both cars were road-tested under the same conditions that previously triggered the fault to confirm the fix.
The Result
Both R35s are now shifting cleanly with no hesitation or missed gears. The drivetrain warning hasn’t returned across multiple drive cycles and varied conditions. Catching this early saved both owners from accelerated clutch wear and a much bigger bill down the line.