Fault code P0605 is called “Internal Control Module Read Only Memory (ROM) Error” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.
Technical description and explained code P0605
OBD-II code P0605 is defined as “internal permanent memory (ROM) error of the control module”. Set when a permanent memory error is detected in the powertrain control module (PCM).
This code means that a memory read error has been detected for the control module only. The problem may be in the Power Control Module (PCM) or one of the other supporting control modules.
All modules are monitored by the PCM at all stages of vehicle operation and even at idle. The PCM translates these readings and adjusts the power input to control fuel pressure, gear shift, and antilock brake system operation.
Other control modules can be included to support additional functions such as turbocharger, traction control and cruise control. As technology advances, driver assistance features expand and the list of required control modules continues to grow.
OBD-II error code P0605 indicates that the PCM has lost the ability to control one or more control modules. This means that the ability to configure the control module for proper vehicle operation is disabled. Depending on the severity of the fault, it may take several failure cycles for the MIL indication to appear.
Essentially, error P0605 means that there is a permanent memory problem in the powertrain control module (PCM).
Symptoms of vehicle malfunctions
The main signal that an error P0605 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.
It can also be warning signs such as:
- The “Check engine” control lamp on the control panel will light up (the code will be recorded in the memory as a fault).
- Floating revolutions, as well as attempts to stall at idle.
- Multiple handling problems.
- Sharp or unstable shifting of automatic transmission.
- Reduced engine power.
- Increased fuel consumption.
- Problems with a particular system, indicating a possible loss of communication in that area.
Code P0605 indicates a RAM error. Depending on what the failure affects, the error may be severe or moderate.
Factors that can cause this error code
The error code P0605 can mean that one or more of the following problems have occurred:
- Powertrain Control Module (PCM) programming error.
- If the engine control module has been replaced, it may need to be programmed.
- Bad power supply relay of ECM / PCM.
- Open or short circuit in wiring harness.
- Loose or damaged connectors.
- Poor grounding is a common cause.
- Blown engine-ECU fuse.
- CAN bus may be faulty and have a short to ground or wire breakage.
- Sometimes the cause is a faulty PCM module.
How to fix or reset OBD-2 code P0605
Some suggested steps for troubleshooting and fix the error code P0605:
- Read all stored data and error codes with an OBD-II scan tool. To find out when and under what circumstances error P0605 appeared.
- Clear the error codes from the computer memory and test-drive the vehicle to find out if the malfunction appears again.
- If the error code appears again, visually inspect the electrical wires and powertrain control module (PCM) connector.
- Measure battery voltage and compare it to the manufacturer’s specification.
- Check continuity of powertrain control module (PCM) power and ground circuits with multimeter.
- Try reprogramming the control module.
- Evaluate powertrain control module (PCM) operation following vehicle manufacturer’s procedure.
- Clear the error code from the computer memory again, and test drive the vehicle to see if the problem is resolved.
Diagnose and repair of problems
To correct code P0605, the most common solution is to replace and reprogram the PCM. Although, faulty wiring should also be considered as a cause of this error.
Perform a thorough visual inspection of all points where the wiring rests on the body. These points represent ground connections. You will often find loose connections or even ground straps that hang down after unrelated repairs have been made.
If bad ground connections have been found and repaired, remove all codes and re-scan the system to see if any codes return. In some cases it may be necessary to re-integrate or even reprogram some controllers after a communication failure.
If all ground connections are secure, perform a thorough visual inspection of all wiring on the vehicle. Note that this inspection may require the removal of the dashboard, seats, carpets, and even trim panels to gain access to all wiring harnesses.
If no wiring damage is found, but the P0605 code remains despite following the steps above. One option may be to replace the entire electrical harness. However, this does not guarantee that the problem will be solved because the problem may be related to the controller.
Typical problems with controllers include faulty drivers, memory failure, or other components for any number of reasons. For this reason, replacing the entire harness is not recommended. Until exhaustive diagnostic tests have been performed on all controllers, including the PCM.
Checking and reprogramming
If the PCM has recently been replaced, there is a good chance that it has been improperly programmed or not programmed at all. In addition, you cannot use a controller from another vehicle. Unless it has been reprogrammed specifically for the vehicle in question.
Aftermarket (high performance) firmware may not be recognized by other controllers, resulting in a stored P0605.
Improperly programmed or replaced controllers may be reprogrammed by the factory scan tool. If you can’t access such a scanner, most dealerships offer PCM programming for a nominal fee.
Some aftermarket PCM manufacturers offer preprogrammed controllers for certain models. Contact your auto parts supplier and get the vehicle identification number, mileage, and other pertinent data.
On which vehicles does this problem occur most frequently
Fault code P0605 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
- Audi
- Chevrolet (Cruze, Epica)
- Chrysler (PT Cruiser, Sebring)
- Dodge (Caravan, RAM)
- Ford (F-150, Focus)
- Hyundai (Santa Fe, ix35)
- Infiniti
- Jaguar
- Jeep
- Kia (Optima, Sorento, Sportage)
- Mercedes-Benz
- Nissan (Almera, March, Micra, Murano, Note, Primera, Qashqai, Sentra, Teana, Tiida, X-Trail)
- Ssangyong (Actyon)
- Subaru
- Toyota
- Volkswagen
Fault code P0605 can sometimes be found with other errors. The most common are the following: P0104, P0305, P0456, P0513, P0551, P0600, P0601, P0602, P0603, P0604, P0606, P0607, P0608, P0609, P0610, P0700, P0705, P1391, P1611, B1352.
