P062D – Fuel Injector Driver Circuit Performance

Reinier

By Reinier (Contact Me)
Last Updated 2017-03-04
Automobile Repair Shop Owner

Trouble CodeFault LocationProbable Cause
P062D Fuel Injector Driver Circuit Performance Wiring, Defective fuel injector / injector circuit or software, PCM

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What Does Code P062D 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.

What are the common causes of code P062D?

Some common causes of code P062D could include the following-

  • Damaged, burnt, shorted, disconnected, or corroded wiring and/or connectors
  • Defective fuel injector(s)
  • Defective injection driver circuit(s), or corrupted software
  • Failed or failing PCM. Note that while this is a rare event with regard to most other codes, it is often the cause of P062D/P062E. Despite this though, all other possible causes must be investigated and eliminated before any controller is replaced.

What are the symptoms of code P062D?

Some common symptoms of code P062D could include the following-

  • Stored trouble code and an illuminated warning light
  • In almost all instances of this code, the engine will be forced into a fail-safe, or limp mode until the ignition is turned off.
  • In many cases, the engine will not start again until the problem is resolved
  • If the engine does start, idling will be rough or erratic
  • If the engine idles, it may not be possible to raise the engine speed above idling speed

How do you troubleshoot code P062D?

SPECIAL NOTES: It should be noted that although it does happen, code P062D rarely appears in isolation. This code is almost invariably accompanied by other codes that most often relate to misfires, or injector issues on specific cylinders, which sometimes makes it very difficult to determine the root cause of the problem, and especially if an oscilloscope with which to check the operation of the injector driver circuit(s) is not available.

Thus, if an oscilloscope (and relevant reference data) is not available, the diagnostic and repair options that are available to non-professional mechanics are limited to inspecting injector wiring harnesses for poor connections, damage or short circuits, or perhaps to swapping out suspect injectors with injectors that are known to be good. If these measures do not resolve the problem, the only other viable option is to refer the vehicle for professional diagnosis and repair. END OF SPECIAL NOTES.    

Step 1

Record all fault codes present, as well as all available freeze frame data. This information can be of use should an intermittent fault be diagnosed later on.

Step 2

If an oscilloscope and reference data is available, refer to the manual to identify and locate all the injectors’ electrical connectors, and be sure to disconnect all connectors to prevent the engine from starting.

Follow the instructions in the manual to connect the oscilloscope leads correctly on the effected injectors’ harness, and crank the engine to obtain a waveform on the ‘scope screen. Refer to the image below-

Injector driver waveforms

Note however that although this image is an actual injection waveform, there are differences between the actual waveforms generated by different types of (Saturated or Peak and Hold) injectors, as well as between different brands of injectors. Nonetheless, the dashed line in the bottom waveform represents an abnormal injection confirmation signal, and confirms that code P062D has set as a result of this abnormal signal.

From the above, it should be obvious why having access to an oscilloscope and accurate reference data is required to verify the existence of an abnormal injection conformation signal. Without this information, the diagnostic procedure has to be performed largely “blind”, meaning that it might be impossible to trace the root cause of the problem short of replacing parts, components, and/or wiring in the hopes of stumbling onto the solution.

NOTE: “EDU” in the image refers to the injector driver circuits in the PCM. Refer to the manual for the application being worked on for the exact terminology or abbreviation used by the manufacturer to describe the injection driver circuit(s).

Step 3

Regardless of whether an oscilloscope has confirmed the presence of an abnormal injection conformation signal or not, the next step involves inspecting the affected injectors’ wiring for damage, short circuits, open circuits, or signs of corrosion in the wiring and/or connectors.

However, resist the temptation to repair wiring if abnormalities are found. In these cases, it is always better to replace damaged wiring with complete OEM harnesses to prevent the possibility of poorly executed repairs causing resistance or continuity issues later on.

Clear all codes after all repairs/replacements are complete, and start, and let the engine idle for few seconds before scanning the system again to see if the code returns.

Step 4

If the code persists, but all wiring is free of visible defects, prepare to test the affected injector’s wiring for resistance and continuity, but be sure to disconnect injector harness from the PCM to prevent damage to the PCM, but more specifically, to the injector driver circuits.

Compare all obtained readings with the values stated in the manual, and replace the effected injectors’ wiring with an OEM harness if discrepancies are found. Clear all codes after repairs are complete, and start, and let the engine idle for few seconds before scanning the system again to see if the code returns.

Step 5

If the code persists, but all wiring is free of visible defects and known to be good, suspect a faulty injector, or PCM/injector driver circuit. However, there is a far bigger chance that an injector had failed, as opposed to the PCM, so resist the temptation to condemn the PCM out of hand.

Refer to the manual for detailed information on how to test the internal resistance of the affected injector(s), but bear in mind that “close enough” is NOT good enough. There are very good reasons why fuel injectors on any given application have a specific resistance, so make sure that the injectors under investigation have resistances that fall within the manufacturers’ specifications. Replace all injectors whose resistance does not meet specified values, but only use OEM parts to ensure a successful repair.

Clear all codes after all repairs/replacements are complete, and start, and let the engine idle for few seconds before scanning the system again to see if the code returns.

NOTE: A fuel injectors’ internal resistance is a reasonably good indicator of its overall condition, but it does not necessarily follow that a fuel injector is good merely because its resistance meets the specified value. Long use in extreme environmental conditions and bad fuel can affect fuel injectors in various ways, one of which is making the injector’s moving parts stick due to corrosion or excessive mechanical wear. In some cases, this can cause code P062D and other injector related codes to set, so replace all injectors at least once every 150 000 miles or so to prevent this type of problem.

Step 6

If the code persists beyond Step 5, there is not much more (if anything) the average non-professional mechanic can do to resolve the problem apart from blindly replacing parts and components, which approach is NOT recommended.

At this point, it is likely that replacing the PCM and/or injector driver circuits is the only viable solution, but doing this requires that the replacement PCM be programmed, and that several relearning procedures be carried out to ensure that the replacement PCM work as intended.

While it is possible to do all of the above on a DIY basis, the better option would be to refer the application to the dealer or other competent repair shop for professional assistance with the required reprogramming/relearning procedure(s).

Codes Related to P062D

  • P062E – Relates to “Fuel Injector Driver Circuit Performance – Bank 2”

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