P2A7CAlternative Fuel Hydraulic Pressure Sensor Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2A7C is set when the hydraulic pressure sensor signal falls below its valid band, most often from a signal wire grounded against the chassis, an open 5 V reference or a sensor with an internal short. If this sensor watches the return side, as in one of Caterpillar's layouts, a dead-low reading would hardly stand out at first, since return pressure is low anyway; the range check against the minimum voltage still catches it. On the drive side a low value can mask the pressure rise that marks a completed stroke. The control may then rely on the remaining sensor or stop the LNG pump. Where both pressure sensors share a reference wire, check whether P2A77 is stored too. No manufacturer documents P2A7C or its thresholds.
- What you may notice
- Warning lamp on
- Pump stops or delivers less LNG
- Additional sensor codes if the reference is shared
- Likely causes
- LikelySignal wire grounded against chassis or hydraulic lines
- PossibleOpen 5 V reference to the sensor
- RareSensor shorted internally
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.