What it means
The alternative fuel pump B compression stroke valve control is not behaving as expected.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
Alternative fuel pump B’s compression-stroke valve controls fuel delivery during the pump’s compression stroke. The control module monitors whether the valve circuit and response behave as expected, and sets P2A84 when pump B’s control response falls outside the expected range or performance.
Common causes
Most likely first.
- Compression stroke valve sticking or binding
- Fault in valve wiring or connector
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 the freeze-frame data and review live data for pump B’s valve command and response, noting the load and engine speed when the fault appears.
- Inspect pump B’s valve connector and wiring for loose terminals, corrosion, chafing, or other damage that could disrupt the control signal.
- Check the valve and its linkage, where accessible, for signs of sticking or binding.
- Test the pump B valve circuit and coil according to the wiring diagram and compare measurements with the manufacturer’s specification.
- If the electrical checks pass, use the manufacturer’s procedure to assess whether the compression-stroke valve moves and responds correctly.
Common fixes
- Clean and secure a loose or corroded pump B valve connector.
- Repair damaged wiring or terminals in pump B’s valve circuit.
- Correct a sticking or binding compression-stroke valve if the manufacturer’s service procedure permits it.
- Replace pump B’s compression-stroke valve if it fails the specified electrical or response test.
Can I keep driving?
Avoid high loads and rapid acceleration because an erratic pump B valve response can lead to poor fuel delivery, reduced power, or stalling. Stop driving if the engine stalls or cannot maintain safe 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.