What it means
The adaptive learning offset for fuel pressure regulator B has reached the upper limit. Long-term drift upward indicates progressive wear of the regulator or a return path that is becoming restricted.
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 helps hold fuel-rail pressure near the control module's target. This code sets when the learned correction for regulator B reaches its upper limit, showing that the module has run out of adjustment while pressure trends too high.
Common causes
Most likely first.
- Fuel pressure regulator B sticking or faulty
- Restricted fuel return or regulator outlet
- Fuel pressure sensor signal biased high
- Regulator control circuit fault
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
- Check freeze-frame and fuel-pressure data to confirm that measured pressure is above target and the learned correction is at its upper limit.
- Inspect regulator B and its connector and wiring for damage, corrosion, or loose pins.
- Check the regulator outlet and fuel return path for a restriction that could prevent pressure from relieving.
- Observe commanded and measured pressure while the module operates regulator B, using the vehicle's service procedure.
- Test the pressure-sensor signal for a high bias and check the regulator control circuit before condemning the regulator.
Common fixes
- Repair a damaged regulator control wire or connector.
- Clear a restriction in the return line or regulator outlet.
- Replace a pressure sensor confirmed to report pressure too high.
- Replace regulator B if it sticks or cannot respond correctly to commands.
Can I keep driving?
Avoid high engine speeds and heavy acceleration because pressure control may worsen and cause poor running or stalling. If starting becomes unreliable or the engine stalls, stop driving and arrange repair.
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.