P01A6: Alternative Fuel Rail Pressure Sensor Circuit High

What it means

Alt fuel rail pressure sensor signal voltage above expected range. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

The alternative-fuel rail pressure sensor reports rail pressure to the powertrain control module. The module monitors the sensor signal circuit and sets P01A6 when the signal is higher than its expected electrical range, which can make the reported pressure unreliable.

Common causes

Most likely first.

1. Signal wire open
2. Connector pins corroded - high contact resistance
3. Supply wire pinched against B+ source

Symptoms

• Check-engine light on
• Alternative-fuel pressure reading may be inaccurate or unavailable
• Poor running or reduced power may occur

How to diagnose it

1. Use a scan tool to record freeze-frame data and compare the alternative-fuel rail pressure reading with other available pressure or operating data.
2. Inspect the rail pressure sensor connector and harness for moisture, corrosion, backed-out pins, chafing, or damage near hot or moving parts.
3. With the code active, gently move the sensor harness while watching the pressure reading for a change that points to an intermittent connection.
4. Check the sensor signal wire for an open and inspect the supply wiring for a short to battery voltage, following the vehicle wiring diagram.
5. If wiring and connections are sound, test the sensor and its supply and ground circuits against the manufacturer's specification.

Common fixes

• Repair chafed or open wiring in the alternative-fuel rail pressure sensor circuit.
• Clean or replace corroded terminals and secure any backed-out pins at the sensor connector.
• Repair a supply wire shorted to battery voltage.
• Replace the rail pressure sensor if its output fails the manufacturer's test.

Can I keep driving?

If the engine runs normally, limit driving and avoid heavy acceleration because the alternative-fuel pressure reading may be unreliable. Stop if power drops or the engine runs poorly, and arrange diagnosis promptly.