What it means
The alternative fuel hydraulic fuel pump select valve control circuit signal is intermittent or erratic.
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
The module controls the alternative-fuel hydraulic pump select valve through an electrical circuit and monitors the signal for stable operation. P2A74 sets when that signal cuts in and out or varies erratically, often because a connector or harness connection changes with movement or vibration.
Common causes
Most likely first.
- Valve connector not seated
- Harness chafing intermittently shorts the wire
- Connector with intermittent contact under vibration
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
- Review freeze-frame data and code status to see whether the fault appeared during vibration, load changes, or a particular operating condition.
- Inspect that the select-valve connector is fully seated and check for corrosion, loose pins, or a damaged latch.
- Examine the valve harness for chafing or intermittent contact with nearby parts, especially where it bends or moves.
- Monitor the circuit signal or valve response with a scan tool while gently moving the harness, following safe test procedures.
- Check continuity and terminal fit through the circuit, then test the select valve if the wiring remains stable.
Common fixes
- Reseat and secure the select-valve connector.
- Repair chafed or intermittently shorting harness wiring.
- Replace damaged connector terminals that lose contact under vibration.
- Replace the select valve if it has an intermittent internal electrical fault confirmed by testing.
Can I keep driving?
Because an intermittent fault can cause sudden hesitation, stalling, or power loss under load, avoid high-speed or high-load driving until the connection is repaired. Stop if the engine stalls or power loss makes traffic operation unsafe.
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.