Code P2607 indicates that the powertrain control module (PCM) has detected a lower than expected voltage in the control circuit for the 'B' intake air heater. This component is typically used on diesel engines to pre-heat intake air for easier cold starting and reduced emissions during warmup.
The heater grid itself can short internally or fail, drawing too much current or causing a low voltage condition in the circuit.
Chafed wires shorted to ground, corroded pins, or loose connections in the heater circuit can cause a low voltage signal to the PCM.
The relay that supplies high-current power to the heater may be stuck closed or have internal shorting, affecting the control circuit.
If the temperature sensor reports abnormally low temperatures, it may incorrectly command the heater on continuously, triggering circuit faults.
The control module's internal driver circuit for the heater may have failed, though this is rare and should only be considered after all wiring and components are verified.
It is generally safe to drive, but in cold weather you may experience hard starting, rough idling, and increased white smoke until the engine warms up.
Intake air heaters are almost exclusively found on diesel engines, so this code typically applies to diesel vehicles equipped with grid heaters.
No, replacing the PCM is usually incorrect for P2607. The problem is almost always a failed heater element, a damaged wire, or a faulty relay. PCM failure is the last resort.
Diagnosing this requires a digital multimeter to test resistance and voltage. If you are comfortable with electrical testing, it is manageable, but accurate diagnosis is necessary to avoid replacing good parts.