P0204
P0204: meaning, possible causes, and diagnosis
The computer detected an electrical problem in the control circuit for injector 4. The code does not prove that the injector itself is faulty.
Updated: 2026-10-26
What it means in plain language
The computer detected an electrical problem in the control circuit for injector 4. The code does not prove that the injector itself is faulty.
Technical definition
Injector circuit/open, cylinder 4.
What this code does not confirm
A code identifies a condition monitored by the vehicle computer. By itself, it does not prove which part failed or authorize replacing one.
Possible diagnostic paths
1
Wire, connector or injector power to be checked
Technical explanation
An interruption, abnormal resistance or poor connection may prevent the module from controlling the injector.
Plain-language explanation
The electrical current may not be coming correctly to the indicated injector.
How it is checked
Inspect visible damage and check feed, continuity and control only with the correct diagram.
When a correction is appropriate
No puentes terminales ni apliques voltaje sin conocer el circuito. The correction is decided only after locating and confirming the defect.
Go to a professional to measure the circuit if you don't have the right diagram and equipment.
2
Injector or control stage to be checked
Technical explanation
The controlled component or the electronic stage that activates it may not respond as expected by the module.
Plain-language explanation
The injector or whoever activates it may not be responding, but the code doesn't say which one.
How it is checked
Follow the electrical and functional test of the manufacturer before removing any fuel components.
When a correction is appropriate
No cambies el inyector ni el módulo basándote únicamente en el código. The correction is decided only after locating and confirming the defect.
Pressurized fuel and module testing shall be kept in trained hands.
Information that makes the diagnosis more specific
- Exact brand, model, year, version and engine.
- All the codes present and their OBD status.
- Freeze frame and live data related to the system.
- Symptoms, mileage and recent maintenance history.
- Procedure and limits of an authorised source for that vehicle.
Sources and scope
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Audi A3 Quick Reference Specification Book
Audi of America / archivo NHTSA · 2026-10-26
It supports the punctual definition of the code; It does not identify a cause, a part or a repair.
-
Frequently Asked Questions About On-Board Diagnostics
U.S. Environmental Protection Agency · 2026-10-26
Supports the safety difference between a fixed breakdown lamp and a flashing lamp; It doesn't diagnose the cause.
How this article was prepared
White Hat Mgmt LLC wrote this explanation from Juan el Mecánico’s structured diagnostic record and the cited sources. Automation only formats and translates reviewed content; it does not invent causes, parts, prices, or procedures.
Educational guidance only. It does not replace an inspection or service information for the exact vehicle.
Common questions
What does code P0204 mean?
The computer detected an electrical problem in the control circuit for injector 4. The code does not prove that the injector itself is faulty.
Does P0204 confirm a failed part?
No. The code directs attention to one or more systems, but the cause must be confirmed with tests and vehicle-specific information.
Can I keep driving with P0204?
The code alone cannot answer that. Safety symptoms and the way the vehicle behaves take priority.
What information should I collect next?
Record every code and status, the symptoms, when the light appeared, and the vehicle details. Keep the freeze-frame values and units if the scanner provides them.