B0309 Bmw M1 Diagnostic Trouble Code

B0309 Bmw M1 code definition:
B0309 is a kind of OBD-II Diagnostic B-Body Diagnostic Trouble Code for Bmw M1.

B0309 Bmw M1 is defined as Cylinder 3 Injector Circuit Malfunction. This code means the PCM (powertrain control module, also known as ECM or engine control) has detected a problem in the injector or its wiring, or in injector circuit for cylinder 3. There are two wires dedicated for each coil; one is battery feed which usually comes from the distribution center, and the other one for the coil driver circuit from the PCM. The PCM grounds or ungrounds the circuit to activate or deactivate the coil.

Symptoms

Symptoms of a B0309 Bmw M1 diagnostic trouble code may include:
  • Cherry red hot catalytic converter
  • Poor acceleration
  • The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
  • Rich or lean exhaust
Place of B0309 in engine

Possible Causes :

  • Faulty IMRC actuator relay (if equipped)
  • A large air leak at or near the number one oxygen sensor would also cause a lean mixture.
  • An air leak forward of the DPF will change the sensor readings resulting in the code

Common Misdiagnoses

  1. IC Circuit High Voltage Problem
  2. Control Module Throttle Actuator Position Performance Problem
  3. Air Conditioning (A/C) Clutch Feedback Circuit High Voltage Problem
  4. Cruise Vehicle Speed/Set Speed Difference Too High Problem
  5. PCM Stack Overrun Problem

Repair Processes :

Use the DVOM to test resistance and continuity on all system circuits if actuator and sensor resistance levels are in compliance with manufacturer's specifications. With the valve disconnected, the red voltmeter lead should be attached to the IMRC valve power wire and the black voltmeter lead connected to ground.

Process Tips

Diagnostic trouble code B0309 Bmw M1 is not difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.

Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before B0309 Bmw M1.

Fortunately, B0309 Bmw M1 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

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