What the P0203 code means?

The P0203 is a diagnostic trouble code that is set when the engine control module (ECM) has detected a fault in the injector circuit for cylinder 3. The ECM looks for a specific range of voltage and resistance from each injector circuit and when the results are found to be out-of-range, a diagnostic trouble code (DTC) will be set.

What causes the P0203 code?

The most common cause of this code is damage to wiring caused by wildlife. The warm area atop the engine provides shelter for small animals, where they proceed to gnaw the wiring for some strange reason. Other causes include a faulty fuel injector, corroded electrical wiring or connector faces, or a faulty fuel injector driver in the PCM.

What are the symptoms of the P0203 code?

1. Poor acceleration and lack of power
2. Engine running rough
3. Engine dies or may not start at all
4. Excessive fuel consumption

Common mistakes when diagnosing the P0203 code:

Keep in mind that PCM failure is rare. Often the PCM is replaced in error because of open or shorted circuits in the fuel injection system.

What repairs can fix the P0203 code?

Repair or replacement of wiring harness
Cylinder 3 injector replacement
ECM replacement
Connection issues fixed