P109D Diagnostic Trouble Code

P109D is a kind of OBD-II Diagnostic P-Powertrain Diagnostic Trouble Code.

It is considered generic because it applies to all makes and models of vehicles, although specific repair steps may be different depending on your car model.

Symptoms

Symptoms of a P109D diagnostic trouble code may include:

Malfunction Indicator Lamp (MIL) illuminated
Carbon Buildup on O2 Sensor
Poor fuel economy
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.

Possible Causes :

Low fuel pressure caused by a clogged filter, failing fuel pump, failed fuel pressure regulator or clogged or leaking injectors.
Low fuel pressure caused by a clogged filter, failing fuel pump, failed fuel pressure regulator or clogged or leaking injectors.
A large vacuum leak would cause a massive amount of un-metered air to enter the intake manifold resulting in an overly lean mixture.

Repair Processes :

Look for damage to the tank indicating impact that may have damaged the fuel pump or sender. If you find a related TSB, the information will often help in diagnosing the code in question as TSBs are crested from many thousands of repairs.

Process Tips

Diagnostic trouble code P109D 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 P109D.

Fortunately, P109D is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

P109D Trouble Code For Specific Cars

P109D Daihatsu D-compact Gear Shift Position Circuit [senses forward / rearward position, odd / even gears]
P109D Bmw Z3 Column Tilt Feedback Potentiometer Circuit Open
P109D Mercedes C 320 ABS Inlet Valve Coil LR Circuit Short To Ground
P109D Duesenberg A Illuminated Entry Relay Short To Battery
P109D Volkswagen Crafter Reverse Output Circuit
P109D Willys-overland 77
P109D Simca Plein Interior Scanning Sensor Circuit Failure