What does it mean?
SPECIAL NOTES: Non-professional mechanics should take note that diagnosing code P062D reliably requires the use of an oscilloscope, and accurate reference data in the form of a waveform library for the application being worked on. If neither an oscilloscope, nor reference data is available, the wiser option is to refer the vehicle to the dealer, or other competent repair shop for professional diagnosis and repair. END OF SPECIAL NOTES.
OBD II fault code P062D is a generic code that is defined as “Fuel Injector Driver Circuit Performance – Bank 1”, and is set when the PCM (Powertrain Control Module) detects an inconsistency between the number injection command, and injection confirmation signals for one or more fuel injectors.
Typically, this code sets on the first failure cycle that occurs after the engine had been running for a period of time set by the manufacturer, which is usually between about 0.5, and 1 second. “Bank 1” refers to the bank of cylinders that contains cylinder #1 on engines with two cylinder heads.
Modern fuel injection systems have reached a very high state of development, and ever-more sophisticated electronic systems are required to both control fuel injection pulses, and to monitor the system to maintain peak performance.
One such control mechanism is a feedback, or injection confirmation signal that alerts the PCM to the fact that the injection signal had been received, and provided the injector is serviceable and that all other requirements are met, it will inject the required volume of fuel into the cylinder.
We need not delve into the complexities of how the PCM calculates the injection timing here, beyond saying that once the PCM has determined the exact moment of injection, it grounds the injection command signal for that injector, thus completing the circuit that allows the injector to open. However, the PCM also needs to know that the injector has received the injection signal, and to accomplish this, the signal is grounded across both a Field Effect Transistor and a serial resistor.
This has the effect of creating a measurable voltage drop in the circuit, with the difference between the injection command signal, and the returned signal representing a confirmation that the injection command signal had been received by the injector.
In practice though, the voltage drop (and hence, the difference between the injection command and confirmation signals), can change or vary for a number of reasons, chief among which are failures of injector solenoid coils, and short/open circuits in an injector’s control circuit.
The injector driver circuits in the PCM monitor the injection confirmation signals continually, and in the event that the voltage drop exceeds a specified level relative to the current drawn by an injector, no confirmation signal is, or can be generated. When this happens, the injector driver circuits disable the affected injector, but it should be noted that injectors are almost invariably paired.
For instance, on a 4-cylinder engine, the pairing might be injectors #1 / #4 , and injectors #2 / #3, which means that if injector #1 our example engine is disabled, # 4 will be disabled as well. Moreover, when code P062D is set as a result of no injection confirmation signals being generated on one or more injectors, the PCM will force the engine into a fail-safe or limp mode, which will endure until the ignition is turned off.