P0201

Code P0201 means the engine control module (ECM) has detected a malfunction in the fuel injector circuit for cylinder 1. The ECM monitors the voltage and resistance of each injector circuit, and when cylinder 1's readings fall outside the expected range, this code is stored. This is distinct from a misfire code (P0301), as it specifically points to an electrical problem in the injector circuit rather than a combustion failure.

You'll likely notice the engine running rough, especially at idle, along with reduced power and possibly increased fuel consumption. The engine may shake or vibrate noticeably because one cylinder isn't firing correctly. In some cases, unburned fuel can pass into the exhaust, producing a fuel smell and potentially damaging the catalytic converter over time.

A useful diagnostic technique is to swap the cylinder 1 injector with another cylinder's injector. If the code follows the injector to the new cylinder (e.g., changes to P0203), the injector itself is faulty and needs replacement. If the code stays on cylinder 1, the problem is in the wiring or connector. Individual fuel injectors typically cost $50 to $150 for most vehicles, making this a reasonable DIY repair if you're comfortable working around the fuel system.

Severity

Symptoms

• •Check Engine light is on
• •Engine misfires or runs rough especially at idle
• •Noticeable loss of power during acceleration
• •Increased fuel consumption
• •Engine vibration or shaking
• •Possible fuel smell from exhaust

Likely Causes

Estimated Cost

Common Fixes

1. Replace the cylinder 1 fuel injector
2. Repair or replace damaged wiring to the cylinder 1 injector
3. Clean or replace the corroded injector electrical connector
4. Swap injectors between cylinders to confirm the faulty component

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