I have a few SC-811s and HU-xxx but i didn't much like the the HU-xxx with the built in CD player. I did however find the issue with my SC-901! From looking online it seems to be a common problem with the 900/901 units and I found the culprit, on the right side of the unit (front facing you) theres ...

ECU Tuning : $20 per ECU What I can offer: -Injector calibration for swapped injectors. -Manual transmission binary flash for manual swapped 850s. -Rear O2 disable and other CEL disables. -Enabling the use of A/C after a M4.4 swap. I will not tune the ECU for increased HP as I do not want to be res...