What it means
The supply line that powers the solenoid of fuel pressure regulator B is open. Without supply the regulator cannot operate and the ECU cannot maintain rail pressure on this stage; sets when the controller sees no current flow even with the solenoid commanded on.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Fuel pressure regulator B's solenoid needs an electrical supply to control its part of the fuel rail pressure system. The engine control module sets P233D when it commands the solenoid on but detects no current flow, consistent with an open supply circuit.
Common causes
Most likely first.
- Supply line open or relay defective
- Fuse for regulator B supply blown
- Pin pushed back out of connector body
Symptoms
- Check engine light on
- Hard start, no start, or stalling under load
- Power loss especially at high load or rpm
- Possible long cranking time
How to diagnose it
- Save freeze-frame data and check live data for regulator B commands and fuel pressure to understand when the fault occurs.
- Inspect regulator B's supply wiring, connector, and related fuse for damage, corrosion, or a terminal pushed back into the connector.
- Check the regulator B supply fuse and relay, if fitted, for an open fuse or failed relay contact.
- With the circuit safely isolated, check continuity through the regulator B supply wire and connectors to locate an open.
- If the supply path is intact, test the solenoid and its control circuit using the manufacturer's procedure.
Common fixes
- Repair an open or damaged regulator B supply wire.
- Seat or replace a pushed-back or damaged connector terminal.
- Replace a blown regulator B fuse after checking for the cause.
- Replace a defective supply relay or regulator B solenoid if testing confirms the fault.
Can I keep driving?
A missing regulator B supply can cause extended cranking, stalling, or power loss, especially under load. Keep trips short and avoid high-load driving; stop if the engine stalls or cannot maintain power.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.