AutoCodes – Mercury – P0204 Mercury

P0204 Mercury Code - Injector Circuit Malfunction Cylinder 4

Quick Answer

The Engine Control Module (ECM) supplies voltage to each fuel injector on the high control circuits. Common causes include Faulty fuel injector 4, Fuel Injector 4 harness is open or shorted, Fuel Injector #4 circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0204 Mercury indicates Injector Circuit Malfunction Cylinder 4.
Common causes: Common causes include Faulty fuel injector 4, Fuel Injector 4 harness is open or shorted, Fuel Injector #4 circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 700

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Jun 01, 2022

Description
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
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Code P0204 Mercury Description

The Engine Control Module (ECM) supplies voltage to each fuel injector on the high control circuits. The ECM energizes each fuel injector by grounding the low control circuit of the fuel injector. The ECM monitors the status of the fuel injector circuits. When a fuel injector circuit condition is detected by the ECM, the affected fuel injector(s) is disabled. The Diagnostic Trouble Code (DTC) will be set when the ECM detects the fuel injector control circuit is open for greater than 2 s.

OBDII Code P0204 Mercury - Injector Circuit Malfunction Cylinder 4 - AutoCodes.com — P0204 Mercury Code - Injector Circuit Malfunction Cylinder 4

What does this mean?

What are the Possible Causes of the DTC P0204 Mercury?

Faulty fuel injector 4
Fuel Injector 4 harness is open or shorted
Fuel Injector #4 circuit poor electrical connection

How to Fix the DTC P0204 Mercury?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

User Submitted Video

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0204 Mercury code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0204 Mercury Code

1. What does the OBDII code P0204 mean on a Mercury?

P0204 indicates a malfunction in the injector circuit for cylinder 4, meaning the engine control module (ECM) is detecting an issue with the fuel injector's electrical circuit.

2. What are the common symptoms of a P0204 code in a Mercury?

Symptoms may include rough idling, engine misfires, reduced fuel efficiency, hesitation during acceleration, and the check engine light turning on.

3. What causes the P0204 code to appear?

Possible causes include a faulty fuel injector, damaged wiring or connectors in the injector circuit, a malfunctioning ECM, or a short circuit in the injector harness.

4. Can I drive my Mercury with the P0204 code?

Driving with a P0204 code is not recommended, as it can lead to poor engine performance, increased emissions, and potential damage to the catalytic converter.

5. How do you diagnose the P0204 code on a Mercury?

Diagnosis involves using an OBDII scanner to confirm the code, inspecting the injector wiring and connectors for damage, testing the fuel injector's resistance, and checking for ECM faults.

6. How do I fix the P0204 code on my Mercury?

Repairs may include replacing the faulty fuel injector, repairing or replacing damaged wiring or connectors, or reprogramming or replacing the ECM if necessary.

7. How much does it cost to fix a P0204 code?

The repair cost depends on the issue, ranging from $150 to $300 for a fuel injector replacement and higher if ECM repairs or wiring replacements are needed.

8. Can a dirty fuel injector cause the P0204 code?

While P0204 typically relates to electrical issues, a clogged injector could mimic similar symptoms. Cleaning the injector might resolve the issue if no electrical faults are found.

9. Will clearing the P0204 code fix the problem?

Clearing the code will remove it temporarily, but the underlying issue must be resolved to prevent the code from returning.

10. How can I prevent the P0204 code from occurring?

Regular maintenance, such as inspecting wiring for damage, using high-quality fuel, and cleaning injectors periodically, can help prevent injector circuit issues.