What Does It Mean?
This diagnostic trouble code (DTC) is a generic powertrain code, meaning it applies to most OBD-II equipped vehicles, including but not limited to VW Volkswagen, Dodge, Ram, Kia, Chevrolet, GMC, Jaguar, Ford, Jeep, Chrysler, Nissan, etc. Although generic, the specific repair steps may vary by make/model.
A stored P021D code means that the Powertrain Control Module (PCM) has detected a malfunction in the fuel injection timing circuit for a specific engine cylinder. In this case, the cylinder in question is cylinder ten. Consult a reliable vehicle information source to determine the exact location of cylinder number ten in the vehicle where the P021D was stored.
Based on my experience, a P021D code is stored exclusively in vehicles equipped with diesel engines. Today’s clean-burning (direct injection) diesel engines require extremely high levels of fuel pressure.
Due to this high fuel pressure level, only qualified personnel should attempt to diagnose or repair the high-pressure fuel system.
When unit injectors are used, the high-pressure injection pump is driven by the engine’s timing chain and timed based on the crankshaft and camshaft positions. Whenever the engine’s crankshaft and camshafts reach a certain point, the high-pressure injection pump is pulsed; resulting in an extreme degree (up to 35,000 psi) of fuel pressure.
Common rail direct injection systems are timed using a common high-pressure fuel rail and individual solenoids for each cylinder. In this type of application, the PCM or a standalone diesel injection controller is used to control injector timing.
Variations in camshaft and/or crankshaft timing alert the PCM to inconsistencies in the specific cylinder injection timing and prompt a stored P021D code. Some vehicles may require multiple ignition cycles with a failure for this type of code to be stored and a malfunction indicator lamp to illuminate.
Related fuel injection timing codes include cylinders 1 through 12: P020A, P020B, P020C, P020D, P020E, P020F, P021A, P021B, P021C, P021D, P021E, and P021F.
Code Severity and Symptoms
All codes related to the high-pressure fuel injection system should be considered severe and addressed with a degree of urgency.
Symptoms of a P021D engine code may include:
Engine misfires, sagging, or stumbling
General lack of engine performance
Characteristic diesel fuel odor
Reduced fuel efficiency
Causes
Possible causes of this P021D code include:
Faulty fuel injection solenoid
Open or shorted wiring and/or connectors in the fuel injector control circuit
Bad fuel injector
Failed engine timing component
Crankshaft or camshaft position sensor (or circuit) failure
Diagnostic and Repair Procedures
I would need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable vehicle information source to diagnose a P021D code.
Start with a visual inspection of components and wiring harnesses related to the high-pressure fuel system. Look for signs of fuel leaks as well as damage to wiring or connectors.
Check for Technical Service Bulletins (TSBs) related to the vehicle, symptoms, and codes in question. If such a TSB is found, it will provide very useful information for diagnosing this code.
Now, connect the scanner to the vehicle’s diagnostic port and retrieve all stored trouble codes and freeze frame data. I like to record this information as it may prove beneficial during diagnosis. Next, I would clear the codes and test-drive the vehicle to see if the code resets. If crankshaft position sensor and/or camshaft position sensor codes are stored, diagnose and repair them before attempting to diagnose the injector timing code.
If the code resets:
If the vehicle in question is equipped with a common rail injection system, use the DVOM and the vehicle information source to test the injector solenoid for the cylinder in question. Any component not meeting manufacturer specifications should be replaced before proceeding. Once suspected parts are repaired/replaced, clear any codes that may have been stored during testing and test-drive the vehicle until the PCM enters readiness mode or the code resets. If the PCM enters readiness mode, you know the repair was successful. If the code resets – you can assume you still have a problem.
If the injector solenoid meets specifications, disconnect the controller and use the DVOM to test the system circuits for shorts or opens. Repair or replace system circuits that do not meet manufacturer specifications according to the pinout chart located in your vehicle information source.
Unit injector failure can almost always be attributed to a failed engine timing component or some type of high-pressure fuel system leak.
A P021D should only be diagnosed by a qualified technician due to extreme fuel pressure
Determine the type of high-pressure fuel system the vehicle is equipped with before starting your diagnosis