P2A6D: Alternative Fuel Rail Pressure Regulator Inlet Pressure Sensor Circuit Intermittent/Erratic

P2A6D is the dropout code of the regulator inlet pressure sensor: the signal jumps or briefly vanishes, but not long enough for a steady low or high verdict. The regulator normally lives in the engine bay, next to the right-hand strut mount on GM's 2015 Impala bi-fuel, and Blackstone requires warm engine coolant to circulate through its SAN209 unit so that it does not ice up. Its connector therefore sees heat, vibration and condensation. Loose terminals, a harness chafed against coolant hoses or moisture inside the plug are the usual suspects. No manufacturer publishes P2A6D; CARB expects circuit faults of such inputs to be detected. Wiggle-test the harness while watching live data, and look for corrosion in the connector.

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, sometimes clearing again
Gas gauge flickers or jumps
Sporadic switch from gas to petrol while driving

Most likely causes

Loose or widened terminal in the sensor connector
Condensation or corrosion in the plug near the coolant-heated regulator
Harness rubbing on hoses or brackets with intermittent contact

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
Gently move the wiring with the engine running and watch whether the reading changes.
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 P2A6D means

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

Frequently asked questions

Can I keep driving with code P2A6D?

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 P2A6D?

The most common causes are: loose or widened terminal in the sensor connector; condensation or corrosion in the plug near the coolant-heated regulator; harness rubbing on hoses or brackets with intermittent contact.

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.