P2A7A is the general circuit fault of the alternative fuel hydraulic pressure sensor, a measuring point that the code list keeps apart from the hydraulic pump pressure sensor of P2A75. Where it sits is not defined publicly, and no manufacturer documents the split. Patents for hydraulically driven LNG pumps show the candidates: Caterpillar's US9228574B2 places one sensor in the supply line and another in the return line to the reservoir, while Westport's US8726785B2 suggests one sensor per side of the drive piston when pressure is taken at the drive unit. P2A7A is stored when the signal is faulty but fits neither a clear low nor a clear high case. Pump control then lacks one input and may restrict LNG delivery. P2A7C and P2A7D name low and high.
High severity. Can I keep driving?If you smell gas, do not keep driving or start the engine: move away and call for assistance. With no smell, drive moderately to an authorized shop.
Symptoms
- Warning lamp on
- Reduced LNG delivery or power limitation
Most likely causes
- Damaged connector or harness at the hydraulic sensor
- Hydraulic pressure sensor faulty
- Fault in a sensor reference or ground shared with other sensors
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: hard
- It can trigger limp mode.
- It affects emissions.
What each character of P2A7A means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- A: Hybrid or air and fuel
- 7A: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2A7A?
If you smell gas, do not keep driving or start the engine: move away and call for assistance. With no smell, drive moderately to an authorized shop.
What causes code P2A7A?
The most common causes are: damaged connector or harness at the hydraulic sensor; hydraulic pressure sensor faulty; fault in a sensor reference or ground shared with other sensors.
Related codes
- P2A7BAlternative Fuel Hydraulic Pressure Sensor Range/Performance
- P2A7CAlternative Fuel Hydraulic Pressure Sensor Circuit Low
- P2A7DAlternative Fuel Hydraulic Pressure Sensor Circuit High
- P2A7EAlternative Fuel Hydraulic Pressure Sensor Circuit Intermittent/Erratic
- P2A75Alternative Fuel Hydraulic Pump Pressure Sensor Circuit
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.