P2A78
Alternative Fuel Hydraulic Pump Pressure Sensor Circuit High
Voltage on the alternative fuel hydraulic pump pressure sensor signal line is above the expected window. Wire shorted to B+ or sensor open.
Voltage on the alternative fuel hydraulic pump pressure sensor signal line is above the expected window. Wire shorted to B+ or sensor open.
Common causes
- high
Signal wire shorted to B+
One of the most commonly reported causes for this code — check this first.
Typical part cost: $220-1100
- medium
Open pressure sensor
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 P2A78 mean?
P2A78 means "Alternative Fuel Hydraulic Pump Pressure Sensor Circuit High". It is a generic OBD-II code that points to a fault in the auxiliary emission controls.
What are the most common causes of P2A78?
signal wire shorted to b+; open pressure sensor; 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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