What is SPN 158 FMI 2?
SPN 158 FMI 2 is a diagnostic trouble code (DTC) that indicates a low voltage condition to the engine control module (ECM). The ECM is the computer that controls the engine, and it needs a certain amount of voltage to operate properly. If the voltage is too low, the ECM can malfunction or even shut down completely.
What are the symptoms of SPN 158 FMI 2?
The symptoms of SPN 158 FMI 2 can vary depending on the severity of the voltage problem. In some cases, the engine may run rough or hesitate. In other cases, the engine may stall or refuse to start. Additionally, the engine may display warning lights or messages on the instrument panel.
What are the causes of SPN 158 FMI 2?
There are a number of possible causes of SPN 158 FMI 2. These include:
- Low battery voltage: The most common cause of SPN 158 FMI 2 is low battery voltage. This can be caused by a number of factors, such as a weak battery, a faulty charging system, or a parasitic draw on the electrical system.
- Loose or corroded battery connections: Loose or corroded battery connections can prevent the ECM from getting the voltage it needs.
- Faulty wiring: Faulty wiring between the battery and the ECM can also cause SPN 158 FMI 2.
- Faulty ECM: In rare cases, SPN 158 FMI 2 can be caused by a faulty ECM.
How to diagnose SPN 158 FMI 2
To diagnose SPN 158 FMI 2, a diesel engine technician will need to use a diagnostic scanner to read the DTCs from the ECM. The technician will also need to check the battery voltage, the battery connections, and the wiring between the battery and the ECM.
How to fix SPN 158 FMI 2
The repair for SPN 158 FMI 2 will depend on the cause of the problem. If the problem is caused by low battery voltage, the technician will need to charge the battery or replace it. If the problem is caused by loose or corroded battery connections, the technician will need to clean and tighten the connections. If the problem is caused by faulty wiring, the technician will need to repair or replace the wiring. If the problem is caused by a faulty ECM, the technician will need to replace the ECM.
Prevention
There are a number of things you can do to prevent SPN 158 FMI 2:
- Keep your battery in good condition: Make sure your battery is properly charged and that the connections are clean and tight. You should also have your battery tested regularly.
- Maintain your charging system: Make sure your charging system is in good working order. This includes the alternator, the voltage regulator, and the wiring.
- Check for parasitic draws: A parasitic draw is a small electrical current that is draining the battery even when the car is turned off. If you suspect there may be a parasitic draw, have your car checked by a qualified technician.
