P01C9 code meaning
Fuel Rail/System Pressure - Too High Bank 2
Powertrain system Generic code P01xx codes Check engine light
What P01C9 means
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.
P01C9 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P01C9
- Check engine light on (possibly intermittent)
- Noise from the bank 2 high-pressure pump
- Slightly reduced power possible
Common causes of P01C9
- Most 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
- Less likelyPressure relief path blocked
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
High pressure fuel pump bank2Fuel volume control valveFuel rail bank2
What each part of P01C9 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 1 | Area: fuel and air metering. |
| C9 | The exact fault in that area. |
What to do next
- Note P01C9 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P01C9
What does P01C9 mean?
P01C9 means "Fuel Rail/System Pressure - Too High Bank 2". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P01C9?
Drive gently and only to a workshop. With P01C9 the car can go into limp mode (reduced power) to protect itself.
Will P01C9 fail an emissions test?
Yes, it can. P01C9 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P01C9 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P01C9 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.