P0602 OBD-II Trouble Code: Control Module Programming Error

P0602 code definition

When the Powertrain Control Module stores a P0602 trouble code, it usually indicates a programming error in one of the control modules, including the transmission control module, the antilock brake control module, the anti-theft module, the body control module, the climate control module, the cruise control module, the fuel injection control module, the instrument panel control module, proximity alert module, the traction control module, and the turbo control module. Additional, related codes include P0601, P0603, P0604, and P0605.

What the P0602 code means

A P0602 trouble code signifies problems with a control module, in addition to a programming error within the one of the control modules. The mechanic should keep in mind that some vehicles require multiple drive cycles, upwards of eight, before the check engine light is lit, though the PCM still stores the code upon first occurrence.

What causes the P0602 code?

A poor electrical connection or defective driver in the PCM are the most likely causes for this code to be stored. Additionally, corroded, damaged, or faulty wiring or connectors within the Control Area Network (CAN) Bus harness or a loose or broken wire or ground strap can also cause this code. A defective CAN Bus is also sometimes to blame.

What are the symptoms of the P0602 code?

Symptoms of a P0602 trouble code include problems driving and shifting, engine stalls, and rough idling. In addition to these symptoms, cars with this stored code also suffer from poor acceleration and a decrease in the vehicle's fuel economy.

How does a mechanic diagnose the P0602 code?

To diagnose a P0602 trouble code, the mechanic needs to complete the following steps while using an appropriate OBD-II scanner and a digital volt/ohmmeter:

• Inspect all wiring, connectors, and components, looking for any loose connections or damage.
• Download any freeze frame data and stored trouble codes. This information can come in handy when trying to determine the order in which the trouble codes were stored.
• The mechanic should clear the code and then test drive the vehicle to see if the code returns.
• If the code returns, the mechanic should connect a specialized scanner, such as one from Autohex or Tech 2, to try and determine the cause of the code storage more quickly. Otherwise, the diagnostic process can become time consuming and cost prohibitive for the mechanic. The mechanic should test any circuitry while the vehicle is in operation for best results.
• The mechanic should install some sort of memory saving device or run the risk of having to reprogram the PCM and other control modules if a probe is misplaced.
• Next, test the continuity and ground with the battery of all associated control modules using the digital volt/ohmmeter, making sure to use an auxiliary ground cable.
• Using a CAN Bus system wiring diagram, test the continuity between the individual control modules.
• Finally, clear and test the system to see if the code returns.

Common mistakes when diagnosing the P0602 code

Common mistakes by mechanics when diagnosing a P0602 trouble code include mistaking another code, such as codes dealing with engine misfires, lean exhaust, or the fuel injector, as the cause of the vehicle's problems. This misdiagnosis can lead to an unsuccessful repair and a return of the code. Mechanics can avoid this misdiagnosis by repairing and clearing all trouble codes in the order they were stored on the PCM.

How serious is the P0602 code?

In addition to decreases in vehicle performance, such as acceleration, shifting, and idling, a P0602 trouble code can also affect fuel mileage, making the vehicle less efficient.

What repairs can fix the P0602 code?

Once the mechanic has diagnosed the problem, they should set about repairing the vehicle and trying to clear the P0602 trouble code. This process includes making the following repairs if needed:

• Replace any faulty or damaged wiring, connectors, or components. The mechanic should also make sure that all connectors are securely connected.
• After testing the individual control modules, replace any that are faulty.
• Replace the PCM if the fault lies there.

Need help with a P0602 code?

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