P0602 – Engine control module (ECM) -programming error

By Benjamin Jerew (Contact Me)
Last Updated 2016-04-01
ASE Master Tech

Table of Contents

1. What Does Code P0602 Mean?
2. What are the common causes of code P0602 ?
3. What are the symptoms of code P0602 ?
4. How do you troubleshoot code P0602 ?
5. Codes Related to P0602
6. Get Help with P0602

What Does Code P0602 Mean?

At its core, the modern internal combustion engine is essentially the same as it has been for over a century. What’s really changed has been the addition of sensors and electronic controls, which has greatly improved power output, fuel economy, and emissions. At any given moment, down to the millisecond-level, the ECM is monitoring sensor readings, making calculations, and making minute adjustments to your engine’s function.

To achieve this level of control, ECM programming, as well as that of other system control modules, is so complicated and precise that automakers really don’t want anyone messing with it. Tampered or faulty programming could result in problems, such as poor fuel economy, poor combustion, or abnormal wear and mechanical failure.

All the information that the ECM needs, to manage your engine, is encoded in onboard memory, one type of which is referred to as EEPROM (electronically erasable programmable read only memory). Generally, EEPROM is programmed at the factory, programming depending on the vehicle, powertrain, transmission, trim level, and other vehicle-specific modules. Certain ECMs may also be programmable using factory scan tools. Some aftermarket mods may include such a feature. If the ECM detects that its memory doesn’t match what is expected or has been compromised, it sets DTC P0602, “Engine Control Module (ECM) Programming Error,” and illuminates the malfunction indicator lamp (MIL).

What are the common causes of code P0602 ?

DTC P0602 may have number of causes. Here are some of the most common.

• New ECM – If the ECM has been replaced, it may need to be programmed. If it isn’t programmed for your specific vehicle, it may not work at all.
• Wrong ECM – Similarly, if the wrong ECM is installed, it may not be able to communicate with other modules.
• Tampered ECM – Some aftermarket performance modifications may include ECM reprogramming. The ECM may not recognize the foreign program.
• Faulty ECM – Again, it isn’t unheard of, but ECM failure is a fairly rare occurrence.

What are the symptoms of code P0602 ?

Depending on the failure mode of your vehicle, aside from the MIL, you may or may not notice any drivability problems. Some vehicles may go into a “limp-home” mode, cutting out certain gears in the transmission, while other vehicles may not start at all.

How do you troubleshoot code P0602 ?

Because this DTC refers to a programming error, your ability to diagnose and repair this problem may be limited, and you may need professional assistance.

• Clear Codes – First, try clearing codes and restarting the vehicle. It’s possible, however improbable, that you got a false DTC.
  • Regarding false DTCs, while any ECM fault is recorded, do not attempt to diagnose any other DTCs until the ECM DTC is repaired. Communication, programming, or memory faults may cause other erroneous DTCs.
• Power Check – The ECM needs at least 12.5 V to function. Low voltage does all kinds of weird things to electronic systems. Check and repair, if necessary, the following.
  • Make sure the battery measures at least 12.6 V, with the car off. If you can start the vehicle, you should measure at least 13.2 V, with the engine running.
  • Check the battery terminals, clamps, and ground wire for corrosion and excessive resistance.
  • Check all fuses and make sure ECM connectors are properly connected.
• ECM Check – Has the ECM or any other module been replaced? If this is the case, the new ECM or other module may not have been programmed or paired properly.

At this point, you may need the assistance of a professional with a factory scan tool. Some vehicles may have TSBs pertaining to this issue, and any reprogramming would likely only be a factory scan tool function.

Codes Related to P0602

• DTC P0600 Serial Communication Link
• DTC P0601 Internal Control Module Memory Check Sum Error
• DTC P0603 Internal Control Module Keep Alive Memory (KAM) Error
• DTC P0604 Internal Control Module Random Access Memory (RAM) Error
• DTC P0605 Internal Control Module Read Only Memory (ROM) Error
• DTC P0606 ECM/PCM Processor
• DTC P0607 Control Module Performance

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