What it means
The supply line that powers the solenoid of fuel pressure regulator B is below the expected voltage with the regulator commanded active - typically a high-resistance feed, partial short to ground or weak relay contact.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Regulator B's solenoid supply provides the electrical power it needs to help control fuel rail pressure. P233E is set when the engine control module detects that this feed falls below the expected level while the solenoid is commanded active, as can happen with excessive resistance or a partial short to ground.
Common causes
Most likely first.
- Supply feed has high contact resistance
- Partial short to ground on supply line
- Connector pins corroded - high contact resistance
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
- Record freeze-frame data and compare regulator B command, supply voltage, and fuel pressure in live data to identify when the feed drops.
- Inspect the regulator B supply wire, fuse, relay, and connector for corrosion, heat damage, loose terminals, or rubbed insulation.
- Check the fuse and relay contacts for damage or excessive resistance, following the manufacturer's procedure.
- Measure voltage drop along the regulator B supply path while the solenoid is commanded on, and compare it with the manufacturer's specification.
- If the feed wiring checks out, test for a partial short to ground and check the solenoid against the manufacturer's specifications.
Common fixes
- Clean or replace corroded regulator B supply terminals.
- Repair a high-resistance or damaged supply wire or connector.
- Repair a supply wire that is partially shorted to ground.
- Replace a faulty relay, fuse connection, or regulator B solenoid when testing confirms the cause.
Can I keep driving?
The low supply may keep regulator B from controlling fuel pressure, leading to hard starting, stalling, or power loss under load. Avoid demanding acceleration and stop if the engine stalls or loses 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.