Broken, chafed, or corroded wiring in the fuel pressure regulator solenoid supply circuit; Loose or damaged electrical connector at the fuel pressure regulator solenoid; Failed fuel pressure regulator solenoid (open internal coil); Blown fuse or faulty relay that supplies power to the solenoid circuit; Corrosion or water intrusion in the wiring harness or connector; Faulty powertrain control module driver circuit (less common)

DTC codes / P00xx · Fuel and air metering and auxiliary emission controls / P00C8

P00C8Fuel Pressure Regulator A Solenoid Supply Voltage Control Circuit/Open

P00C8 indicates that the powertrain control module has detected an open circuit or supply voltage fault on the control circuit for the fuel pressure regulator A solenoid. The computer commands a specific current to the solenoid, but the circuit does not carry the expected voltage, so the regulator cannot be controlled as intended.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering and auxiliary emission controls

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Rough idle or stumbling when the engine is cold or under light load
Hesitation or a flat spot during acceleration
Reduced fuel economy due to incorrect fuel pressure regulation
In rare cases, a no-start condition if the solenoid circuit is completely open

Common causes, most likely first

Broken, chafed, or corroded wiring in the fuel pressure regulator solenoid supply circuit
Loose or damaged electrical connector at the fuel pressure regulator solenoid
Failed fuel pressure regulator solenoid (open internal coil)
Blown fuse or faulty relay that supplies power to the solenoid circuit
Corrosion or water intrusion in the wiring harness or connector
Faulty powertrain control module driver circuit (less common)

How to diagnose and fix it

Check the fuse and relay that supply power to the fuel pressure regulator solenoid circuit
Inspect the wiring harness and connector at the solenoid for damage, corrosion, or looseness
Measure resistance across the solenoid coil to check for an open circuit
Backprobe the control circuit at the solenoid and verify voltage with the key on and during cranking
Check for continuity between the solenoid connector and the powertrain control module to rule out an open wire
If the circuit is intact, test the powertrain control module output with a known-good load or oscilloscope
Replace the faulty solenoid, wiring, or connector as needed and clear the code

Don't overlook the simple circuit checks

A loose ground connection for the fuel pressure regulator solenoid can mimic an open circuit and set P00C8 even when the solenoid itself is good.
The code can be set intermittently by vibration or heat, so a wiggle test of the harness while monitoring live data is often more revealing than a static resistance check.
Some vehicles use a shared power supply for multiple solenoids, so a blown fuse may cause additional codes that point away from the actual fault.
Replacing the fuel pressure regulator solenoid without first verifying the supply voltage and ground can lead to a repeat failure if the underlying wiring issue is not corrected.
P00C8 is strictly an electrical circuit fault; it does not indicate a mechanical failure of the fuel pressure regulator or a low fuel pressure condition.

Can I keep driving with P00C8?

You can usually drive the vehicle with P00C8 set, but expect reduced performance and fuel economy, and avoid heavy acceleration or towing until the fault is repaired. If the engine runs rough or stalls, stop driving and have the circuit inspected promptly.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.