P01C9Fuel Rail/System Pressure - Too High Bank 2
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- Some V engines have a separate high-pressure fuel circuit per bank, each with its own pump or rail – for example Audi's 4.0 TFSI V8 with a second high-pressure pump for bank 2. These codes are the bank 2 counterparts of the system pressure codes for bank 1. P01C9 is the bank 2 counterpart of P0088: the actual pressure is above target. Audi documents it on 2013–2014 A8/S8 and S6/S7 4.0 TFSI models together with P0088: at low supply voltage the duty cycle of the volume control valve was no longer sufficient, the valve stayed shut and the pump delivered full flow – audible as noise from pump 2, sometimes with slightly reduced power. The fix was a software update. Not every two-rail engine uses them: GM's LT6 reports bank 2 pressure problems under other codes.
- What you may notice
- Check engine light on (possibly intermittent)
- Noise from the bank 2 high-pressure pump
- Slightly reduced power possible
- Likely causes
- LikelyVolume control valve not controlled properly (e.g. at low supply voltage), software
- PossibleVolume control valve sticking
- PossibleBank 2 rail pressure sensor reading too high
- RarePressure relief path blocked
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €0 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.