P264D: A Rocker Arm Actuator Position Sensor Circuit High Bank 1

What it means

The position sensor signal is above the upper diagnostic threshold. Common causes are an open sensor or a short to the 5 V reference.

At a glance

• Usually lights the check-engine light

How it works

The rocker arm actuator position sensor on bank 1 tells the controller which valve lift mode is active. This code sets when its signal exceeds the upper limit, commonly because the sensor circuit is open or the signal wire is shorted to the reference supply.

Common causes

Most likely first.

1. Open sensor element
2. Signal wire shorted to the 5 V reference
3. Connector pins corroded - high contact resistance

Symptoms

• Check-engine light
• Reduced engine power or acceleration
• Rough running or engine misfire

How to diagnose it

1. Record freeze-frame data and inspect live bank 1 position data for a reading pinned high or unchanged as the commanded mode changes.
2. Inspect the bank 1 sensor connector and harness for disconnected pins, broken wires, chafing, or contact with the reference supply wire.
3. Check that the connector is fully seated and its terminals are clean and undamaged.
4. Use the wiring diagram to test the bank 1 signal wire for an open or short to the reference circuit, and check reference and ground circuits to the manufacturer’s specification.
5. If the wiring passes, test the position sensor while commanding actuator movement and replace it if its output remains above specification.

Common fixes

• Reconnect a loose bank 1 position sensor connector.
• Repair an open signal wire or a short between the signal and reference wires.
• Restore damaged or corroded connector terminals.
• Replace the bank 1 position sensor if its internal circuit is open or its output stays high.

Can I keep driving?

If the vehicle runs normally, keep any necessary trip short and avoid hard acceleration because the controller may not know the actual lift mode. Stop if power drops sharply or the engine runs roughly.