P2A70: Alternative Fuel Hydraulic Fuel Pump Select Valve Control Circuit

What it means

The alternative fuel hydraulic fuel pump select valve control circuit has a fault that may prevent the valve from being controlled 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

The alternative-fuel hydraulic pump select valve directs or selects hydraulic pump operation, and the control module monitors its control circuit. P2A70 sets when the circuit has a fault that can prevent the module from controlling the valve as intended.

Common causes

Most likely first.

1. Select valve failed
2. Wiring or connector 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

1. Record freeze-frame data and any related codes, then check whether starting trouble or stalling coincided with a change in alternative-fuel pump operation.
2. Inspect the select valve connector and harness for loose connections, corrosion, chafing, or damage.
3. Use scan-tool commands, if supported, to observe whether the select valve responds when commanded.
4. Test the valve control circuit for continuity, shorts, and power or ground faults according to the wiring diagram.
5. Test the select valve itself using the manufacturer's procedure if the wiring checks pass.

Common fixes

• Reconnect and secure the select valve connector.
• Repair damaged or corroded wiring and terminals in the valve control circuit.
• Replace the select valve if it fails the manufacturer's electrical or functional test.

Can I keep driving?

A hard start, stall, or loss of power under load can make driving unpredictable; avoid high-load driving and stop if the engine stalls or cannot maintain power. Use another fuel mode only if the vehicle supports it and operates reliably that way.