P2509 Code: PCM Power Input Signal Intermittent


Nowadays, cars are equipped with various scanning tools. These tools are helpful to diagnose the problem causing reasons for your vehicle. The PCM or ECM of the vehicles receives input from sensors and controls the key components of the vehicles. When your vehicles are scanned with the P02509 error code, then several questions arise such as causes, reason, diagnosis, and troubleshooting. Let us understand the error code thoroughly.

Definition of P02509

The OBD-II generated trouble code indicates that the PCM input signal is facing some faults.

What does the P02509 error code mean?

The power control module of the vehicle’s engine obtains data from several circuits. Primary function of the Contact relays is to supply voltages to PCM. Various circuits such as voltage circuit, ground circuit, and ignition power circuit are located on the contact relays, as well as PCM receives information through an output signal.


When the ignition switch is turned on, the battery supplies voltages to the engine control module through the relay. By chance the ignition is switched off, the battery power input line supplies voltages to PCM that operates the basic operations of the vehicle.
If the PCM does not receive the voltage as determined within the specifications the PCM will store P02509 DTC and the check engine light illuminates

Possible cause of the P02509 error code

The manufacturer of the vehicle specifies the range of the voltage that each circuit provides input to the ECM. When the voltage range does not fulfill this specification, then the OBD-II scanner generates the P02509 error code that triggers the check engine light to illuminates. Here are some possible reasons that cause PCM not to receive sufficient voltage:

  • Faults in fuse wires
  • Faults in fusible link
  • Faults in circuits
  • Faults in battery
  • Faults in battery cables
  • Faults in PCM relay
  • Faults in the powertrain control module

Symptoms of the P02509 error code

The mandatory symptom of the P2509 error code is the check engine light illuminates. But other symptoms may include:

  • The problem is the engine that causes the Engine shuts down
  • Faults in the engine that leads the engine not to crank
  • Check engine light illuminates
  • Fluctuation in Tachometer
  • Check gauges light may illuminates
  • Vehicle may cut off while driving.

How serious is the P2509 trouble code?

A DTC generated trouble code is considered serious when your vehicle is facing driveability issues. When your vehicle is diagnosed with this error code then there are performance issues that arrived in the vehicle. Sometimes, the vehicle may not start or the engine will shut down, all these things affect the performance of the vehicle.

How to diagnose and fix the P2509 error code?

The P02509 error code can be generated from the failure of various components. For the diagnosis of the cause of the problem, you need to check and repair all components. Once you are done with each check and fix, do a short test drive, and check if codes return. If it returns, check the other components.


For the next step, inspect the ECM wirings and the battery cables, if you notice burnt, shorted, or damaged wires, fix them or replace them. These problems may arise because of loose connections, corrosion, and some other conditions that could affect the functionality of the ECM.

In case, your problem does not solve, for the next step you should check the fusible link and the fuses if you found any faults, repair or replace them.

Check the battery or the charging system of the battery; sometimes they are also responsible for the damages.

If the problem does not solve yet, there may be some problem in the relay. Check the faulty relay by putting the ignition key on and turn on the car. If the dashboard does not illuminate the P02509 error code light, but the scanner is showing the code, then there is a problem in the relay.

In case, after doing all these steps your error code does not go away, there may be a fault in ECM. You need to replace or reprogram the ECM, so that your error code does not return.

The P02509 error code can generate from various possible causes, you should take your car to the potential mechanic and do the required repairing of the wires or the ECM.

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