Common Symptoms of a Failing PCM | Module Experts

As the primary computer control for your vehicle, your powertrain control module (PCM) plays a vital role in ensuring that your engine and transmission work in tandem. When your PCM fails, it typically exhibits one or more different behaviors. Knowing these symptoms can help you pinpoint the root cause of the problem so you can get your vehicle back up and running.

  1. Voltage Overloads

If a solenoid or actuator circuit in your vehicle shorts out or has another issue that compromises its performance, your first sign may be the failure of your PCM. Typically, during diagnostics testing a trouble code will help pinpoint if the PCM is faulty. It is important to note however, the electrical issue that caused the PCM to experience voltage overload in the first place must be adequately addressed or the new PCM could fail for the same reason.

  1. Environmental Factors

As a highly sophisticated computer module, your PCM can be adversely affected by environmental factors that can cause it to fail. Water is the primary element to avoid as exposure to it can render the PCM irreparable. Other environmental factors that could lead to PCM failure include thermal stress due to excessive heat and excessive vibration that causes sensitive parts to fail.

  1. Car May Not Run (will not crank, cranks but will not start)

The PCM is responsible for ensuring that the crankshaft and camshaft is positioned correctly so your engine will turn over. The PCM is also designed to control both ignition timing and spark. Problems with the PCM often result in the vehicle not running at all. In other cases, the vehicle may run poorly. Continuing to run a vehicle with a bad PCM could cause further damage.

  1. Emissions

Because the PCM controls the emissions of your car, a failed emissions test or the presence of oddly-colored or foul smelling exhaust may be a sign that your PCM is going bad.

  1. Check Engine Light (CEL) or Other Error Lights

A malfunctioning PCM will activate dashboard error lights. In fact, you can expect that these lights will flash off and on if the PCM is not able to read the sensors correctly. Your vehicle performance will suffer greatly and may go into limp-mode.

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