P00C6
Fuel Rail Pressure Too Low - Engine Cranking Bank 1.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 0
- AreaFuel and air metering, auxiliary emission controls
- C6
- FaultThe specific fault in that area
What it means
P00C6 is the generic code for fuel rail pressure that is too low while the engine is cranking (Bank 1). During cranking the engine control unit compares the pressure reported by the fuel rail pressure sensor with the pressure it expects, and it sets the code when the rail fails to build enough pressure to start the engine. It is most often linked with long cranking or no-start conditions, and the fault can be in either the low pressure or high pressure side of the fuel system, depending on the engine.
Symptoms
- Long cranking before the engine starts
- Engine cranks but will not start
- Hard starting, especially when hot or cold
- Engine starts then stalls straight away
- Malfunction indicator lamp on
- Possible reduced power or limp mode once running
Possible causes
- Weak or failing low pressure fuel pump, or a blocked fuel filter or pick-up strainerlikely
- Worn or failing high pressure fuel pump (direct injection or common rail engines)likely
- Faulty fuel rail pressure sensor or its wiring, connector or reference supplypossible
- Fuel pressure regulator or pressure control valve stuck open or faultypossible
- Leaking or stuck open injector, or an external fuel leak, preventing the rail building pressurepossible
- Low fuel level, contaminated or wrong fuel, or air in the fuel systempossible
- Fuel pump relay, fuse or power supply fault, or a fault in the control unitrare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting rail pressure, engine temperature and fuel level when the code set
- Check the fuel level and ask about recent refuelling, since contaminated or wrong fuel can cause low pressure
- Inspect the wiring and connectors at the fuel rail pressure sensor, fuel pump and pressure control valve for damage, corrosion or looseness
- Look for external fuel leaks around the rail, lines and injectors, taking care with fire risk
- Check the fuel pump fuse and relay, and listen for the pump priming when the ignition is switched on
- With a scan tool, compare the actual and requested rail pressure while cranking and check the sensor reading with the key on and engine off
- Measure low pressure supply to the high pressure pump and check the fuel filter condition, following the manufacturer's procedure for your engine
- Test the pressure control valve or regulator and perform an injector leak-off or leakage test where the engine type allows
How to fix
- Replace a failed low pressure fuel pump, strainer or clogged fuel filter
- Replace the high pressure fuel pump if it cannot build the specified pressure
- Replace the fuel rail pressure sensor if its readings are wrong or repair damaged wiring and connectors
- Replace a faulty pressure control valve or regulator
- Repair fuel leaks or replace leaking injectors, then bleed the system as the manufacturer specifies
- Drain and clean the system and refill with correct fuel if contamination is found
Can I keep driving?
If the engine starts and runs normally, it can be driven carefully to a workshop, but get it checked soon as the fault may worsen and leave you stranded. Avoid driving if it stalls, loses power or smells of fuel, as a fuel leak is a fire risk.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.