P0602 Code– What Does It Mean | Symptoms | How To Fix It | Cost

P0602 Code– What Does It Mean | Symptoms | How To Fix It | Cost

P0602 is an OBD-II Code that refers to Control Module Programming Error If the vehicle stores this code that means the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) has detected an internal programming error, which applies to the PCM itself.

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?

Poor electrical connection, a programming error, or defective PCM driver are the three most likely causes for Error Code P0602. Other possible causes include:

➢ Defective, corroded, or damaged connectors or wirings within CAN (Control Area Network) Bus harness

➢ Crushed ground wire, or loose module ground strap

➢ Defective CAN bus

➢ New or wrong PCM

➢ Installed aftermarket (high-performance) PCM program

➢ Blown PCM fuse

➢ Poor PCM power supply relay

➢ Open or shorted wiring in CAN harness

➢ This may be due to a new inappropriate PCM

Common Symptoms:

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

➢ Start condition is unavailable.

➢ Occurrence of multiple driving problems.

➢ The automatic transmission shifting is erratic/very harsh.

➢ The fuel proficiency is reduced.

➢ The engine may stand still or Inactive roughly

➢ Engine stalling or rough idling

➢ Harsh or erratic shifting in transmission


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

➢ Observe all wiring, connectors, and elements, looking for any loose connections or damage.

➢ Download any freeze frame data and collected trouble codes. This information can come in advantageous when trying to determine the order in which the trouble codes were stored.

➢ The mechanic should clear the code and then experiment 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-forbidding for the mechanic. The mechanic should test any circuitry when the vehicle is in operation for the 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:

Some of the common mistakes while you diagnose a P0602 trouble code will include mistaking other trouble codes like dealing with engine misfires, lean exhaust, or the fuel injector as the reason for the error code in vehicle. If you do not properly diagnose it can become failed where the error code may return again. The misdiagnosis can be avoided by repairing the damaged part and wiping the diagnostic trouble codes where they are stored in the PCM.

How To Fix-

After a searching diagnosis, the technicians will be able to come up with the right repair route for the error code, which usually includes:

➢ Replacing damaged connectors, components, or wirings, and make sure all connectors are secured

➢ Replacing of faulty components in individual control modules

➢ Replacing faulty PCM

The most common misdiagnosis for this error code is mistaking it with codes relating to engine misfire, lean exhaust, or fuel injector, which would possibly lead to misdiagnosis and unsuccessful repair. Aside from the reducing in vehicle performance characterized by poor acceleration, shifting, and idling, Error Code P0602 can definitely affect fuel mileage, making the vehicle less fuel-efficient.

Related Codes:

  1. P0601 Internal Control Module Memory Check Sum Error
  2. P0603 Internal Control Module Keep Alive Memory (KAM) Error
  3. P0604 Internal Control Module Random Access Memory (RAM) Error
  4. P0605 Internal Control Module Read Only Memory (ROM) Error

How Serious Is This?

A P0602 code is often considered by technicians to be the most important of all. Because it affects multiple systems (powertrain, body, and chassis controls, among others). If left unattended, this fault may lead to other problems in the vehicle’s computerized control system.

How Much Does It Cost To Fix The P0602 Code?

The repair cost of an error code P0602 varies depending on the type and amount of damage. Some technicians may charge a flat fee that can vary from $100 to $300; others prefer the billing method, where they charge by time and parts used. Other causes include:

➢ Price of individual control modules (some may cost between $500 and $1,000)

➢ Labor rates in your region (average is between $75 and $120 per hour)

➢ Availability of actual replacement parts at local auto-parts stores (pricing varies based on store location)


In conclusion, the P0602 code is one of the most serious trouble codes. It is often connected by other DTCs, which indicates there are several problems in the vehicle’s computerized control system. The damage can be quite costly to repair depending on the cause and available replacement parts (some may cost up to $1,000). Luckily, this code does not mean you need a new or remanufactured PCM; it often means that there is some erosion in your engine wiring harness or corroded connections at the connector plug.

P0602 Code– What Does It Mean | Symptoms | How To Fix It | Cost
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P0602 Code– What Does It Mean | Symptoms | How To Fix It | Cost
A P0602 trouble code signifies problems with a control module, in addition to a programming error within the one of the control modules.
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