P2A77
Alternative Fuel Hydraulic Pump Pressure Sensor Circuit Low
Voltage on the alternative fuel hydraulic pump pressure sensor signal line is below the expected window. Wire shorted to ground or sensor short.
Voltage on the alternative fuel hydraulic pump pressure sensor signal line is below the expected window. Wire shorted to ground or sensor short.
Common causes
- high
Signal wire shorted to ground
One of the most commonly reported causes for this code — check this first.
Typical part cost: $220-1100
- medium
Internal sensor short
A plausible cause — test and verify before replacing parts.
Typical part cost: $220-1100
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First things to check
- 1Confirm the code with a scan tool and check for additional related codes.
- 2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.
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Related codes
See related trouble codes
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Frequently asked questions
What does P2A77 mean?
P2A77 means "Alternative Fuel Hydraulic Pump Pressure Sensor Circuit Low". It is a generic OBD-II code that points to a fault in the auxiliary emission controls.
What are the most common causes of P2A77?
signal wire shorted to ground; internal sensor short; connector pins corroded - high contact resistance — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.
Can I keep driving with this code?
This code can put the vehicle into limp or reduced-power mode. Avoid extended driving and have the vehicle diagnosed promptly. Use the Wrenchify app for a full diagnosis specific to your vehicle.
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