What it means
On many platforms, C0075 is an electrical fault in the RF (#2) solenoid circuit (open/short/out-of-range). However, Subaru issued a bulletin where C0075 related to wheel-cylinder pressure sensor inputs affected by air in hydraulic lines or an improperly adjusted brake-light switch—a clear example that definitions vary by OEM. Verify by VIN. AA1 Car+1
Why it sets (generic solenoid logic)
Commanded valve does not produce expected current/voltage feedback, or the circuit is open/shorted. AA1 Car
Symptoms
- ABS/ESC lamps; abnormal RF modulation in ABS events.
- On Subaru cases per TSB: VDC warning; stored C0075 without coil faults due to hydraulic air or BLS mis-adjustment. OEMDTC
Common causes
- Solenoid coil/harness faults at the HCU connector (many GM/Ford).
- EBCM driver failure.
- Subaru-specific: air in brake lines; brake-light switch out of spec. AA1 Car+1
Diagnostics
- Confirm OEM definition for the vehicle (Subaru vs others). OEMDTC
- If solenoid-type: perform bidirectional actuation, coil resistance, and voltage-drop tests; inspect terminals for corrosion/push-outs.
- If Subaru per TSB: bleed the hydraulic system, then inspect/adjust BLS; clear and re-evaluate. OEMDTC
Fixes
- Repair wiring/terminals or replace HCU/EBCM for confirmed coil/driver faults.
- Subaru case: bleed system; adjust/replace BLS per bulletin. OEMDTC
Sources: Generic lists mapping C0075 = RF solenoid #2; Subaru OEM TSB explicitly tying C0075 to hydraulic/pressure-sensor logic and BLS adjustment. AA1 Car+1