What does it mean?
Before it will inject on a common-rail system the module needs a minimum pressure in the rail, because below that value the injectors cannot atomise fuel properly. This code is stored when, during cranking, the pressure measured on bank 2 fails to reach that minimum within the expected number of engine revolutions. The monitor runs only while the starter is turning the engine, which separates it from the running pressure codes and points the diagnosis at the supply side and at how fast the high-pressure pump can build pressure at cranking speed. A pressure shortfall while cranking is caused either by too little fuel reaching the pump, by a pump or control valve that cannot hold what it makes, or by leakage back to the tank through the injectors.
Symptoms
- The engine cranks normally but will not start, or starts only after an unusually long crank.
- Starting is worst when the fuel level is low or after the vehicle has stood overnight.
- The engine may fire briefly and then stall before it settles.
- MIL (check engine lamp) on with the code stored after the failed start attempt.
- Once running, the engine can be down on power or hesitant if the supply restriction is still present.
- No audible prime from the fuel pump area at key-on, or a change in pump noise.
Likely causes
- Weak or failed low-pressure lift pump, so the high-pressure pump on bank 2 is not supplied while cranking.
- Clogged fuel filter or a restricted supply line starving the pump exactly when demand is highest.
- Air drawn into the low-pressure circuit through a loose union, a cracked pipe or a leaking filter housing seal.
- Pressure control or volume control valve stuck open, dumping pressure back to the tank as fast as it is generated.
- Leaking injectors on bank 2 returning excessive fuel, so the rail never fills.
- Worn high-pressure pump unable to build pressure at the low speeds reached during cranking, a problem made worse by slow cranking from a weak battery, poor connections or a tired starter.
- Bank 2 rail pressure sensor reading low or its wiring adding a voltage drop.
How to fix it
- Check fuel level and fuel quality first, then confirm that the low-pressure pump primes at key-on and holds the specified supply pressure while cranking.
- Log live rail pressure during cranking, note the peak reached, and compare it with the start threshold and with bank 1.
- Inspect the fuel filter and supply lines for restriction and renew a filter that is due or contaminated.
- Look for bubbles in a clear section of the supply or return line and pressure-test the low-pressure circuit for air being drawn in on the suction side.
- Carry out an injector back-leak test on bank 2 and, where the system allows, cap the return to see whether pressure then builds.
- Test the pressure control or volume control valve by commanding it closed, or by blocking its return, and check whether cranking pressure rises.
- Verify battery condition and cranking speed before condemning the high-pressure pump, then test pump delivery if everything upstream is proved good.