P0D21 Diagnostic Trouble Code

P0D21 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 P0D21 diagnostic trouble code may include:

Possible spark knock (detonation / pre-ignition)
Poor fuel economy
The engine oil will exhibit dilution from the ECUs attempts to increase engine temperature. Some vehicles advance the fuel injection timing slightly after top center to afterburn a small amount of fuel to increase exhaust temperatures. Some of this fuel enters the crankcase. When the ECU determines the necessity to regenerate the DPF, the service life of the oil be shortened significantly
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.

Possible Causes :

An air leak forward of the DPF will change the sensor readings resulting in the code
Rusty exhaust systems, cracked exhaust manifolds or damaged or missing gaskets or donuts will cause air leaks.
Defective ECU strategies or components will prevent proper regeneration

Repair Processes :

Now, clear the codes and test-drive the vehicle to see if the code is reset. If the engine displays a miss and there wasn't a code, determine which cylinder is misfiring. If the exhaust manifold is visible, spay or pour a small amount of water on each cylinder exhaust port. Water will evaporate immediately on good cylinders and slowly on the missing cylinder. If this can't be accomplished pull the plugs and check the condition. Find out what kind of system you have and verify that voltage to the fuel level sensor is present at the fuel pump wiring harness.

Process Tips

Diagnostic trouble code P0D21 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 P0D21.

Fortunately, P0D21 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

P0D21 Trouble Code For Specific Cars

P0D21 Peugeot 204 ECU A/D Converter
P0D21 Nissan Navara Control Module Long Term Memory Performance/ Immobilizer Code Words Do Not Match
P0D21 Peugeot 309 EGR Flow Out Of Self Test Range
P0D21 Infiniti Q45 SCP (J1850) Invalid or Missing Data for External Lamps
P0D21 Buick Blackhawk Cylinder 5 Misfire Detected
P0D21 Panther Kallista Driver Sid, Side mount Airbag Circuit Open
P0D21 Gmc Suburban Park Brake Switch # 2 Applied Circuit Failure