Caterpillar big engines
Caterpillar puts a time-hold on a LOT of the error/warning signals, assuming that it's probably due to a sensor failure rather than an actual issue. Sometimes 1 hour, sometimes 10 hours (actual "engine running" time, since there is no real-time clock).
So when actual issues DO happen, they are often missed/overlooked. Only the long-term sensor issues got (eventually) noticed and fixed. But between detection and fixing, the issues usually result in merely an error code on the data busses without affecting engine performance .
1. Especially when you set a certain customer parameter to "warning only; don't derate" because the customer attitude is "don't let my vehicle slow down unless the engine actually breaks." My previous role occasionally involved using our CAT service tool software/dongle for telemetry and customer parameters , so it was up to me to build the official list of non-default parameter values to be set at Stryker factories when the engine's control module is powered on for the first time after leaving CAT's factory.
2. But, in light of "right to repair", we didn't have the "CAT engineer's password" that let us mess with the core calibration/fuel map. (There were also MANY mechanical fixes Stryker HQ couldn't do without voiding CAT's engine warranty.) Some colleagues used vehicle acceleration data to challenge Caterpillar that some engines were being shipped with the wrong fuel map, and they were right -- top speed, max torque, and max power had all tested fine in development; the secret was the transient response during acceleration which was hard to pin down.. Customer was much happier when CAT reprogrammed the mini-fleet of Stryker A1 prototypes to, essentially, "go faster."