Faulty bypass valve solenoid or actuator on the 'B' turbocharger/supercharger; Damaged or corroded wiring or connector at the bypass valve control circuit; Vacuum or boost leak in the hose or diaphragm that operates the bypass valve; Sticking or carbon-fouled bypass valve mechanism; Failed PCM driver for the bypass valve control circuit; Restricted or misrouted vacuum supply line to the bypass valve actuator

DTC codes / P00xx · Fuel and air metering and auxiliary emission controls / P00C3

P00C3Turbocharger/Supercharger Bypass Valve B Control Circuit Range/Performance

P00C3 indicates that the powertrain control module (PCM) has detected an out-of-range or performance fault in the control circuit for the bypass valve on the secondary turbocharger or supercharger, designated as 'B'. The PCM monitors the electrical circuit and the valve's mechanical response to commands, and it sets this code when the circuit voltage or valve behavior falls outside the expected range during commanded tests.

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
Reduced engine power or limp mode under acceleration
Poor fuel economy or sluggish throttle response
Audible whistling, hissing, or fluttering noises from the turbocharger area
Rough idle or stalling after deceleration
Inconsistent boost pressure, felt as surging or flat spots during acceleration

Common causes, most likely first

Faulty bypass valve solenoid or actuator on the 'B' turbocharger/supercharger
Damaged or corroded wiring or connector at the bypass valve control circuit
Vacuum or boost leak in the hose or diaphragm that operates the bypass valve
Sticking or carbon-fouled bypass valve mechanism
Failed PCM driver for the bypass valve control circuit
Restricted or misrouted vacuum supply line to the bypass valve actuator

How to diagnose and fix it

Connect a scan tool and record all stored and pending codes, then clear codes and test-drive to see if P00C3 returns
Visually inspect the bypass valve, its connector, and the associated wiring for damage, corrosion, or loose pins
Check the vacuum supply and actuator hose for leaks, cracks, or blockage using a vacuum gauge or smoke tester
Command the bypass valve open and closed with the scan tool and observe whether the valve moves and the circuit responds
Measure resistance and voltage on the control circuit at the valve and at the PCM to isolate an open, short, or high-resistance fault
Remove and inspect the bypass valve for carbon buildup or mechanical binding, cleaning or replacing it as needed
If all external checks pass, perform a continuity and load test on the PCM driver circuit and replace the PCM only after confirming a failed driver

What P00C3 does not always mean

A stuck-open bypass valve often causes no driveability symptoms at all, so the code can appear with only a warning light and no other complaints.
Many technicians replace the bypass valve only to find the real fault is a cracked vacuum hose or a corroded connector pin that was disturbed during the repair.
On twin-turbo systems, the 'B' valve is frequently the secondary turbocharger's valve, and a fault there may be misdiagnosed as a problem with the primary turbocharger.
A weak or failing battery or charging system can cause erratic voltages that the PCM interprets as a bypass valve circuit range fault, so always check system voltage first.
After any repair, the PCM may require a relearn or adaptation drive cycle before the code will clear permanently, and skipping this step leads to false comebacks.

Can I keep driving with P00C3?

You can usually continue driving with P00C3, but avoid heavy acceleration and towing until the fault is repaired, because a bypass valve stuck in the wrong position can cause overboost or underboost and may lead to further damage. If the vehicle enters limp mode or you hear unusual turbo noises, have it checked 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.