P0035 — Turbocharger/Supercharger Bypass Valve A Control Circuit High

Bypass valve A control reports an unexpectedly high electrical condition. An open circuit can also cause this on some systems; the code does not prove overboost.

Affected system: Powertrain

Symptoms

• Engine warning lamp; limited power or weak acceleration.
• Irregular boost response; sometimes only a stored code without clear symptoms.

Possible causes

• Open wire or short to supply, depending on monitor logic.
• Actuator/solenoid electrical fault; investigate the driver only after circuit checks.

What to check

• Identify bypass valve A in engine documentation and read the full subcode; A alone does not identify its location.
• Save failure data and related pressure/position codes; determine whether the fault is constant or command-dependent.
• Inspect the hot-area connector, harness supports and heat damage; check the specified supply and ground.
• Test both opens and supply shorts; on some systems a broken wire can generate circuit high. For a 2017 Civic Type R, check bulletin 18-044 eligibility.
• Verify operation after repair by the OEM method; rod adjustment or turbo replacement does not replace circuit diagnosis.

Also written as: P0035-00, P003500, PO035 (some scan tools add the fault-type byte, e.g. -00).