Fault code P0512 is called “Starter Request Circuit Malfunction” 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 P0512
Stored code P0512 means that the transmission control module has detected a fault in the starter request circuit. In this case, a starter request signal was sent from the PCM, but for some reason the request did not go through.
Although the starter is supplied with DC voltage from the plus wire of the battery, the starter request signal comes from the ignition switch. When the ignition key is placed in the ignition cylinder and turned to the start position.
The electrical part of the ignition switch is then actuated and closes a set of contacts, thereby terminating the starter request circuit. When the starter request circuit is closed, the battery voltage signal is applied to the starter solenoid.
If fault P0512 appears, there may be a problem in the starter request circuit and the PCM has not received the signal.
Even if there are no symptoms, if the PCM does not receive a starter request signal and the engine starts, code P0512 will be stored. The malfunction indicator light may also illuminate.
On some vehicles, it may take several ignition failure cycles for the check lamp to illuminate.
Symptoms of vehicle malfunctions
The main signal that an error P0512 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 written to the ECM memory as a fault).
- The engine may not start.
- Delayed starter or prolonged cranking.
- Cranking the starter without starting the engine.
- There may also be other related trouble codes, such as PCM power circuit or ignition system failure.
- There may be no symptoms other than a stored fault code.
The severity of fault P0512 can be either moderate or high, depending on the symptoms. Of course, if the engine does not start, the code must be eliminated as a matter of urgency.
Factors that can cause this error code
The error code P0512 can mean that one or more of the following problems have occurred:
- Faulty ignition switch.
- Blown fuses or blown fusible link.
- Defective starter relay.
- Open or short circuit in the starter request circuit.
- Insufficient voltage in the system can disrupt operation of a number of vehicle systems.
- Faulty or faulty ECM programming.
How to fix or reset OBD-2 code P0512
Some suggested steps for troubleshooting and fix the error code P0512:
- Read all stored data and error codes with an OBD-II scan tool.
- Clear the error codes from the computer memory.
- Test-drive the vehicle to find out if fault P0512 appears again.
- Visually inspect the fuses or fusible links.
- Check the operation of the ignition switch.
- Check the voltage on the battery and vehicle system.
- If necessary, check relay and starter request circuit operation.
- Test the engine control module (ECM).
Diagnose and repair of problems
Diagnosing the P0512 problem should begin by checking the maintenance bulletins (TSB) for your specific vehicle. Your problem may be known, which can save you time and money during diagnosis.
Do a visual inspection of all relevant wires and connectors, as well as all fuses. Check the starter system fuses when the starter is on. Since fuses in unloaded circuits may appear to be working until the circuit is loaded.
Check the starter relay
If the P0512 problem persists, the starter relay should be checked. The simplest and easiest test is to replace the starter relay with a known good one from another vehicle. If the problem is eliminated, replace the starter relay with a new one.
If there is no replacement relay, you need to find the wiring diagram of the starter system. A view of the starter relay connector will also prove helpful.
Check for a battery voltage input circuit on the starter relay. This circuit should maintain battery voltage when the ignition switch is in the on position.
If there is no voltage to the starter relay, check the system fuses, fusible links and wiring from the battery or battery junction box. In most cases the ignition switch will supply a secondary voltage source signal to the relay when the ignition switch is turned to the start position.
At the same time, the PCM provides a ground signal to the starter relay. The secondary voltage and ground signals cause the contacts inside the relay to close. A completed starter request circuit should send a signal to the starter solenoid and back to the PCM.
Check the voltage signal to the relay from the ignition switch, if there is no signal, then we have a faulty ignition switch or faulty wiring. If the secondary voltage is present, check the ground input signal from the PCM.
No ground signal from the PCM to the starter relay indicates a faulty PCM or programming error.
On which vehicles does this problem occur most frequently
Fault code P0512 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
- Bentley (Azure)
- Ford (Focus)
Fault code P0512 can sometimes be found with other errors. The most common are the following: P0513, P0633.
