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DTC codes / BMW codes / P1414

P1414 · BMWSecondary Air Injection System Monitor Circuit High

P1414 on a BMW means the engine control module (DME) has detected an abnormally high voltage on the secondary air injection system monitor circuit, which is the feedback line from the secondary air pump or its control valve. The DME expects a specific voltage range when the pump is commanded on or off, and a high reading indicates an open circuit, a short to voltage, or a faulty component on that monitoring path.

SystemPowertrain
Code typeBMW specific
SeverityLow
Fix difficultyIntermediate
AreaAuxiliary emission controls

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms.
  • A slight hesitation or rough idle during the first minute after a cold start, when the secondary air system is active.
  • A faint whining or humming noise from the secondary air pump that may be absent or unusually loud.
  • Increased tailpipe emissions during warm-up, which may be noticed during an emissions test.
  • In rare cases, a stored pending code that reappears after clearing without any driveability change.

Common causes, most likely first

  1. Failed secondary air pump motor or worn brushes causing an open circuit in the monitor line.
  2. Corroded, broken, or disconnected wiring or connector at the secondary air pump or combi valve.
  3. Faulty secondary air injection control valve (combi valve) solenoid or stuck valve.
  4. Damaged or shorted monitor circuit wire between the DME and the secondary air pump or valve.
  5. Internal fault in the DME driver circuit for the secondary air monitor.
  6. Blown fuse or relay supplying power to the secondary air pump, leading to a high-voltage signal on the monitor line.

How to diagnose and fix it

  1. Scan all modules and record freeze-frame data to confirm P1414 is the only secondary air code present.
  2. Inspect the secondary air pump connector and wiring for corrosion, chafing, or loose pins, and repair as needed.
  3. Check the fuse and relay that supply power to the secondary air pump, replacing any failed components.
  4. Measure resistance and voltage on the monitor circuit at the DME connector and compare with BMW specifications.
  5. Command the secondary air pump on with a scan tool and listen for operation; if silent, test the pump motor directly.
  6. Test the combi valve for proper vacuum operation and electrical continuity if equipped with a solenoid.
  7. If all external components and wiring test good, suspect the DME and perform a guided diagnostic before replacement.

What the monitor circuit really checks

  • The secondary air monitor circuit often uses a voltage divider inside the DME; a high reading can be caused by a missing ground at the pump rather than a faulty pump itself.
  • A stuck-open combi valve can allow exhaust gas to reach the pump and corrode the monitor circuit, setting P1414 without any pump failure.
  • On many BMW engines, the secondary air pump only runs for 90 seconds after a cold start, so a fault may not appear during a warm-engine test drive.
  • Technicians sometimes replace the air pump when the real problem is a corroded ground strap on the engine block that affects the monitor circuit reference voltage.
  • P1414 can be set by a low battery or charging system issue that causes the DME to see an out-of-range voltage on the monitor line during the self-test.

Can I keep driving with P1414?

The vehicle remains safe to drive because the secondary air system only operates during cold starts to reduce emissions, but prolonged driving with the fault may cause the engine to run slightly richer during warm-up. Avoid extended idling from cold and schedule diagnosis soon to prevent secondary damage to the catalytic converter.

Tools that help

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

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