P01C8: Fuel Rail/System Pressure - Too Low 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. These codes are the bank 2 counterparts of the system pressure codes for bank 1. P01C8 is the bank 2 counterpart of P0087: the actual pressure stays below target over time. Typical causes are a weak high-pressure pump on bank 2, a faulty volume control valve, low supply pressure or a leak. No manufacturer using exactly this code was found; the logic follows P0087 and CARB's requirement for pressure control. Not every two-rail engine uses them: GM's LT6 reports bank 2 pressure problems under other codes.

Bank 2 is the side without cylinder 1, so it only exists on V or boxer engines.

Symptoms

• Check engine light on
• Loss of power or limp mode
• Hard starting, misfires on bank 2

Most likely causes

• High-pressure pump of bank 2 weak or worn
• Volume control valve faulty or its control disturbed
• Supply pressure too low (lift pump, filter)
• Leak in the bank 2 high-pressure circuit

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the pump's fuse, relay, and connector
2. With the connector unplugged, check whether the signal wire is making contact with ground.
3. Replace the filter if it is due for maintenance
4. Compare commanded and actual pressure in live data
5. Measure the pressure with a suitable gauge
6. Check the sensor and regulator before replacing the pump

Good to know

• Repair difficulty: hard
• It can trigger limp mode.
• It affects emissions.

What each character of P01C8 means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• 1: Air and fuel
• C8: Specific fault in that system

Frequently asked questions

Can I keep driving with code P01C8?

Avoid long trips and hard acceleration. If you smell fuel or the car stalls, do not continue.

What causes code P01C8?

The most common causes are: high-pressure pump of bank 2 weak or worn; volume control valve faulty or its control disturbed; supply pressure too low (lift pump, filter).

Related codes

• P0087Fuel Rail/System Pressure - Too Low
• P01C9Fuel Rail/System Pressure - Too High Bank 2
• P01CAFuel Rail Pressure Too Low - Engine Cranking Bank 2
• P01BFFuel Rail Pressure Sensor Circuit Range/Performance Bank 2

Sources

• law.cornell.edu: 13 CCR 1968.2
• static.nhtsa.gov: MC 10122182 9999
• saabwisonline.com: dtc p0087 p0088 or p0089
• static.nhtsa.gov: MC 11009469 0001

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.