Error Code P2668: What It Means & What To Do?

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The trouble code P2668 can be explicated as Fuel Mode Indicator Lamp Control Circuit. This trouble code is generic, which would mean that it can apply to all the vehicles which are equipped with the OBD-II or the vehicles which are made since 1996 up to the present. The specifications on the definition, the troubleshooting steps as well as repairs can always vary from one vehicle make to another. This can happen because of a lot of reasons and the mechanic should diagnose the specific cause for this code.

It is the engine control module which would examine the fuel mode indicator lamp control circuit. This trouble code would be set by the ECM when the fuel mode indicator lamp control circuit would not be as per the parameters set by the manufacturer.

What causes this problem with the Fuel Mode Indicator Lamp Control Circuit?

• Imperfect fuel mode indicator lamp
• Issue of unbolted fuel mode indicator lamp harness
• Unacceptable electrical connection in the fuel mode indicator lamp circuit

1. Fuel Injector - Faulty fuel injector, it will cause rough idles and difficulty in starting. Also, it will affect the fuel economy and engine performance. Fuel injector can also crack or break leading to leakages and should be replaced immediately.
2. Engine Control Module - The solenoid might cause a short in the engine control module because of corrosion in the solenoid or the wire running from the solenoid to the ECM harness.
3. Electronic Control Unit - The ECU power management control module keeps in check the hybrid battery charging functions. If the ECU is faulty, the battery pack will not be able to properly get charged and thus, the ECU might need replacement.
4. Powertrain Control Module - A trouble with the PCM would mean that it is unable to determine the right fuel mixture and would send the car engine either more or less fuel than it requires. Now when the engine gets more, the carbon emission would increase and fuel economy would drop. In case of the opposite, the engine will choke, stutter, and might start stalling sometimes.
5. Diagnostic Tool - Usually any OBD code problem requires deep insight into the problem and high grade tools in order to fix it properly. Thus, buy quality diagnostic tools form us!

It is essential to know the symptoms of an issue as only then you would be able to solve the problem. So that’s why we have listed out some major symptoms of OBD Code P2668 here:

Common Symptoms

• Illumination in the service engine soon light
• Fuel indicator light might not operate properly

If you wish to correct this fault code, then you have to follow certain steps. Correcting a problem needs your careful attention. Here are some ways with the help of which you will be able to correct the OBD Code P2668:

• Repair or replace the quirky fuel mode indicator lamp circuit
• Rehabilitate the defaults in the fuel mode indicator lamp
• Carefully adjust the faults in the fuel mode indicator lamp harness

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If you want to easily diagnose this trouble code, then you must follow the steps which are mentioned here as below:

• A scanner is used by a mechanic to diagnose this fault code. The mechanic will insert a scanner to diagnostic port of the vehicle and recover the codes and freeze frame data. If he happens to find any additional error codes, he has to address them as well. Once it is done, he has to reset the vehicle, and then test drive to see if the error code appears. If the error code does not return, then there can be an erratic condition.
• Then the mechanic has to check the wires, connectors and other electrical components and quickly replace them if he finds them to be damaged or defective. Make sure to retest the entire system after repairs are completed so that you achieve success. Crank the engine and examine the vacuum hoses and throttle air inlet tube for leakage in the vacuum.
• Restore or repair the faulty vacuum lines or constituents as per the need. Then the codes should be cleared up and the entire system should be retested to make sure the issue is repaired. Now if all system wiring, connectors, and constituents including the fuses appear to be in good working condition, then a scanner should be connected to the diagnostic connector. After that the mechanic should record all stored codes as well as freeze frame data.
• These details can prove to be very helpful in diagnosing intermittent conditions that may have contributed to this code being stored. You should continue by clearing the code and then the vehicle should be taken out for a test drive to see if the code returns or not. This will help to decide whether or not the malfunction is intermittent. Now once all the codes have been cleared up, then you should test drive the automobile to see if the code returns.
• If the code is not returning immediately, then you might have an intermittent condition. Intermittent conditions can be quite challenging to diagnose and in extreme cases may have to be allowed to worsen before the right diagnosis can even be attempted.
• This type of code is only applicable for the automobiles with an electronically controlled throttle body. These types of systems are frequently referred to as “drive by wire” throttle bodies. A sensor on the accelerator pedal arm inputs a voltage signal to the powertrain control module or some other associated controller which would command the throttle body opened or closed, it totally depends upon the conditions.
• Voltage signals which are coming from the powertrain control module would activate the throttle actuator motor in the direction which is needed by changing voltage levels and polarity. As the throttle actuator motor turns, it would also turn the gear in the throttle body that is meshed with a bigger gear.
• This change in ratio would allow the throttle plate to open swiftly and suddenly or slowly and gradually, as it all depends upon the commands of the controller. The air intake hose from the throttle body should be carefully removed and with the ignition in the “OFF” position, then you should open the throttle plate.
• Examine the inner bore of the throttle body for immoderate amounts of carbon and then it is essential to clean the bore by utilizing a suitable solvent. The edge of the throttle plate should be cleaned properly. The code should be cleared up and the automobile should be taken out for a test drive to ensure that your repair was successful. Check voltage and ground signals at the throttle actuator control motor connector, when the motor is activated by using a scanner.
• If there is no presence of the voltage and ground signals, then the connector from the PCM should be disconnected and all associated controllers and test individual circuits for resistance and continuity. Repair or restore the open, shorted, or disconnected circuits as per the need.
• Carefully clear the codes and test drive the automobile to ensure a successful repair. If there is a presence of voltage and ground signals at the throttle actuator motor connector, when activated by the scanner, then you must restore the motor, clear the codes, and drive the vehicle to ensure that your repair has been successful
• There are many automakers which would provide service parts for “drive by wire” throttle bodies. It is likely that you might need to restore the entire throttle body, which typically includes the actuator motor as well as the throttle position sensor.
• It is also recommended to replace the pedal sensor with throttle body replacement. You can always consult the vehicle service manual for the particular manufacturer’s recommendations. CAN stands for “controller area network.” The CAN represents a communication bus that would allow a number of microcontrollers to communicate with one another without the need for a host computer.
• It is a message based protocol initially designed for automotive use. The network of CAN bus is actually a complex conglomeration of wiring harnesses and connectors used as a pipeline of information which is shared between two or more automotive control modules.
• Every electrical function of the vehicle is virtually controlled by these controllers, with the powertrain control module being the primary controller. Control modules receive input data from various sensors and emit output signals to system constituents and other control modules. If this proves to be a CAN bus associated situation, then it could prove very challenging to diagnose by an amateur technician.
• Unlike other diagnostic codes, this type of code can sometimes be best left to a professional simply because of the bulk of circuitry involved. An technician which is experienced should use a specialized scanner (Autohex or Tech II) to determine the general area of the malfunction much more rapidly and easily than someone using a code reader as well as a digital volt ohmmeter.
• If you will disconnect and check every single pin of the CAN bus then it can consume a lot of time as well as money. Also make sure to install some type of memory saving device, test the PCM and other controllers lose their memory and sometimes they might require reprogramming. A specialized diagnostic CAN scanner will depict pin values and control module operation without risking a meltdown.
• It can diagnose computer and issues related to circuitry correctly by monitoring automobile operation while the vehicle is being operated. If you want to diagnose this type of code using a digital volt ohmmeter, then it would entail probing thousands of circuits separately.
• One probe which is misplaced could destroy expensive control modules and require that the vehicle be totally reprogrammed. At the most, you may attempt to perform a continuity test after all control modules are disconnected, and this could literally require 40-hours or more, based upon the automobile.
• There are some applications are equipped with up to 18 separate control modules. If you choose to tackle this monumental task, then you must start with a careful visual inspection of all system circuitry, connectors, and fuses.
• Control module ground circuits should be inspected for continuity with battery ground. Generally the faulty system grounds are reason behind the occurrence of these types of codes. An auxiliary ground cable can be supportive in diagnosing system ground discrepancies. Engine and transmission ground cables, straps, and wires are sometimes left dangling once the repairs have been made.
• Search for loose or corroded electrical connectors that might rise the circuit resistance and cause these types of codes to be stored. Obtain a CAN bus system wiring diagram and/or pin out value chart, then use the digital volt ohmmeter to test continuity between individual controller connectors.
• You must compare your findings with the manufacturer’s referenced values and repair open or shorted circuits as per the need. It is more economical to restore the faulty wiring rather than attempting to remove it from the complex web of wiring harnesses.

Common Mistakes When Diagnosing The P2668 Code

• Fuel type select switch related issues
• Quirks in the powertrain control module
• Issues related with the car wiring