P2A6C: Alternative Fuel Rail Pressure Regulator Inlet Pressure Sensor Circuit High

P2A6C means the regulator inlet pressure signal sits above its plausible voltage ceiling. Typical causes are a signal wire touching a 5 V or battery-voltage circuit, an open sensor ground, an open signal line that the module pulls up internally (depending on its design), or an internal transducer fault. Unlike a genuinely excessive cylinder pressure, which P2A6F covers, the value here lies outside anything the sensor can physically deliver. On GM's Impala bi-fuel the regulator-mounted sensor covers a cylinder range of 3,600 psi; ITT's patented regulator places one transducer at the inlet port and a second at the outlet. No manufacturer documents P2A6C with thresholds. A broken ground often pins the reading at maximum, so check ground and connector first.

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

Check engine light on
Gas gauge stuck at full regardless of consumption
Gas mode blocked, bi-fuel vehicle switches to petrol

Most likely causes

Sensor ground open or connector terminal pushed out
Signal wire shorted to 5 V reference or battery voltage
Inlet pressure transducer internally faulty

What to check, in order

Start with the simplest. You can tick off each step.

If you smell gas, shut off the supply, ventilate and do not start the engine
Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
Read the codes with a compatible scanner
Check the connectors and wiring of the component indicated
Leave any work on the gas circuit to an authorized shop

Good to know

Repair difficulty: medium
It can trigger limp mode.
It affects emissions.

What each character of P2A6C means

P: Powertrain: engine and transmission
2: Generic code: same on every make
A: Hybrid or air and fuel
6C: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2A6C?

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 P2A6C?

The most common causes are: sensor ground open or connector terminal pushed out; signal wire shorted to 5 V reference or battery voltage; inlet pressure transducer internally faulty.

Related codes

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.