P00C7

Turbocharger/Supercharger Bypass Valve B Control Circuit Range/Performance

P00C7 is a generic OBD-II powertrain diagnostic trouble code: Turbocharger/Supercharger Bypass Valve B Control Circuit Range/Performance. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P00C7
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on, possible limp mode)
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What P00C7 means

P00C7 is the range/performance fault for Turbocharger/Supercharger Bypass Valve B control circuit. It mirrors P00C5 in diagnostic approach but applies to the second bypass valve in a system that employs two such valves, typically found on twin-turbo engines, sequential turbo systems, or certain V-configuration engines with a turbocharger per cylinder bank.

The code is set when the ECM determines that Bypass Valve B circuit voltage is within acceptable electrical limits but the valve is not performing its intended function. This can be confirmed by boost pressure response checks performed internally by the ECM or through dedicated position feedback. Mechanical causes are the most common: a stuck valve, failed diaphragm, or fouled seat can all allow the solenoid to be energized without the valve moving correctly.

In twin-turbo applications, a non-functional bypass valve on one turbo can result in asymmetric boost delivery, which may manifest as a subtle imbalance in power contribution between cylinder banks. Full diagnostic confirmation requires verifying both the electrical integrity of the circuit and the mechanical response of the valve, combined with live boost pressure data from a scan tool.

Common causes

Most-frequently reported root causes when P00C7 is logged.

  • 1
    Mechanically seized Bypass Valve B due to corrosion or carbon accumulation.
  • 2
    Failed valve diaphragm or actuator mechanism on the B bypass valve.
  • 3
    Cracked, kinked, or disconnected reference hose on vacuum-actuated designs.
  • 4
    Intermittent solenoid electrical connection at the B valve connector.
  • 5
    Internal valve contamination from oil or debris ingestion.
  • 6
    Incorrect bypass valve replacement part with incompatible flow characteristics.
  • 7
    Boost system leak on the B turbocharger circuit affecting ECM performance monitoring.

Symptoms drivers notice

MIL illuminated.
Possible power imbalance between cylinder banks on twin-turbo engines.
Compressor surge on the affected turbocharger.
Inconsistent or reduced boost from the B turbocharger.
Possible hesitation during mid-range acceleration.

How to diagnose P00C7

A typical diagnostic flow when this code is present.

  1. 1
    Scan all modules and record all DTCs; note whether both turbo A and turbo B circuit codes are present.
  2. 2
    Review live boost pressure data for both turbos if individual sensors are available.
  3. 3
    Inspect Bypass Valve B and its connector for mechanical damage, debris, or connector issues.
  4. 4
    Test solenoid B coil resistance against specification with the connector unplugged.
  5. 5
    Inspect vacuum or boost reference hoses on the B valve assembly for deterioration.
  6. 6
    Use scan tool output controls to actuate Bypass Valve B and verify physical response.
  7. 7
    Clean or replace the valve if mechanical sticking is confirmed; repair any electrical fault before condemning the valve.

Related powertrain codes

Frequently asked questions

Which cylinder bank is the B bank?

SAE convention designates the B bank as the passenger-side bank on a V-engine (Bank 2 in most OBD-II naming). However, always confirm with the specific manufacturer's wiring diagram.

Can P00C7 cause damage to the turbocharger?

Yes. If the bypass valve is stuck closed, the compressor cannot vent on throttle lift-off and may experience surge, which over time damages the compressor wheel and bearings.

If only P00C7 is set (not P00C5), does that mean only the B turbo is affected?

Generally yes. If the A bank valve is functioning correctly and only the B valve has a performance issue, P00C7 would be set alone.

Is valve B physically identical to valve A?

On many applications yes, but always verify part numbers from the manufacturer, as flow or actuation pressure specifications can differ in some sequential turbo configurations.

Disabling P00C7 in software

RaceTune can permanently disable P00C7 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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