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DTC codes / BMW codes / P1287

P1287 · BMWSwitching Solenoid for Air Assisted Injection Valves Bank 2 Control Circuit Electrical

P1287 on a BMW indicates that the engine control module (DME) has detected an electrical fault in the control circuit for the bank 2 switching solenoid that operates the air-assisted injection valves. The DME monitors the solenoid's current draw and expects a specific resistance range; when the circuit is open, shorted to ground, or shorted to power, it sets this code. This solenoid is part of the secondary air injection system that helps reduce cold-start emissions by introducing extra air into the exhaust.

SystemPowertrain
Code typeBMW specific
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering (injector circuits)

Symptoms you may notice

  • Illumination of the check engine light (CEL) on the dashboard, often with no other noticeable symptoms.
  • Rough idle or stumbling during cold starts, especially in the first minute after engine start.
  • A slight decrease in fuel economy or a rich-running condition during warm-up.
  • In some cases, a noticeable hissing or whistling sound from the engine bay due to a stuck-open valve.
  • Occasionally, the engine may enter limp mode if the fault triggers other related codes.
  • No symptoms besides the warning light in many instances, as the system is primarily for emissions control.

Common causes, most likely first

  1. Failed switching solenoid for bank 2 air-assisted injection valves (open or shorted coil).
  2. Damaged or corroded wiring harness connector at the solenoid.
  3. Broken, chafed, or shorted wire in the control circuit between the DME and the solenoid.
  4. Faulty DME (engine control module) driver circuit, though rare.
  5. Corrosion or water intrusion in the connector or solenoid, especially on older BMWs.
  6. Loose or missing ground connection for the solenoid circuit.
  7. Aftermarket or incorrect solenoid installed previously, causing resistance mismatch.

How to diagnose and fix it

  1. Clear the code and test-drive to see if it returns; note any freeze-frame data to confirm conditions.
  2. Visually inspect the solenoid connector and wiring for corrosion, damage, or loose pins.
  3. Measure the resistance of the bank 2 switching solenoid with a multimeter and compare to BMW specifications (typically 10–20 ohms).
  4. Check for power and ground signals at the solenoid connector with the key on and during activation; use a noid light or oscilloscope if available.
  5. Perform a voltage drop test on the control circuit to identify excessive resistance or a short.
  6. If the circuit tests good, substitute a known-good solenoid and recheck for the code.
  7. If the solenoid and wiring are intact, diagnose the DME driver circuit or reprogram/replace the DME as a last resort.

Don't overlook the secondary air system

  • A P1287 code often appears alongside other secondary air injection codes like P0411 or P1421, so diagnosing the entire system is more effective than focusing on the solenoid alone.
  • The switching solenoid for air-assisted injection valves is frequently misdiagnosed as a faulty secondary air pump; test the solenoid's resistance and circuit before replacing the pump.
  • On many BMW models, the bank 2 solenoid is located near the exhaust manifold and is exposed to high heat, which can cause the internal coil to fail intermittently when hot.
  • A stuck-open solenoid can cause a lean exhaust condition during cold start, leading to misfire codes and poor driveability that may mask the original P1287.
  • Water intrusion into the solenoid connector from a clogged cowl drain is a common cause on certain BMW platforms, so always check for moisture in the harness.

Can I keep driving with P1287?

You can generally continue driving with P1287, but avoid prolonged idling and cold-start short trips until repaired, as the fault may increase emissions and slightly affect cold-start performance. If the engine runs rough or enters limp mode, have it diagnosed promptly to prevent secondary damage.

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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