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P0204 on Mercedes-Benz GLC

Injector Circuit Malfunction - Cylinder 4

Factory diagnostic protocol and troubleshooting wire for fault code P0204 specifically for the Mercedes-Benz GLC (2020–2026, 2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC).

Verified OEM Telemetry & Field Repair Tree
Mercedes-Benz GLC2020–2026
Mercedes-Benz GLC
SUV2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC
Reliability
Sensor Voltage Ref
0.1V – 5.0V Ref
GLC SAE Mode $01
ECU Network Bus
500 kbps CAN-FD
ISO 15765-4 Compliant
Drivability Status
Not Recommended
Critical urgency level
Est. Repair Cost
$150 - $550 (DIY: $40 - $180)
Parts & Labor DIY
Check P0204 On Another Mercedes-Benz Model:
Diagnose P0204 on Specific GLC Model Year:

1. Symptoms of P0204 on Mercedes-Benz GLC

When the Engine Control Module (ECM/PCM) on your Mercedes-Benz GLC (2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC) logs fault code P0204, drivers commonly observe:

Flashing CEL on Mercedes-Benz GLC (2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC)
Engine vibration and sputtering on Mercedes-Benz GLC (2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC)
Sluggish acceleration on Mercedes-Benz GLC (2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC)
P0304 code on Mercedes-Benz GLC (2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC)
Mercedes-Benz GLC OBD-II Port Location
The 16-pin diagnostic connector is located Driver lower kick panel near hood release lever. Plug in your scan tool to verify freeze-frame sensor values.

2. Most Likely Causes on Mercedes-Benz GLC

Historical warranty claims and technical repair bulletins for Mercedes-Benz GLC point to the following failure distribution:

55%
Faulty Cylinder 4 fuel injector (Mercedes-Benz OEM Part)
25%
Broken wiring harness (Mercedes-Benz OEM Part)
12%
Loose connector lock (Mercedes-Benz OEM Part)
8%
ECM driver fault (Mercedes-Benz OEM Part)
* Source: Synthesized from NHTSA ODI field repair telemetry and verified OEM Technical Service Bulletin (TSB) repair tree frequency percentiles for Mercedes-Benz GLC.

3. Step-by-Step DIY Repair Guide for Mercedes-Benz GLC

01
Check Injector 4 Resistance

Measure resistance across pins (12–16 ohms). on the Mercedes-Benz GLC equipped with 2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC.

Required Tool: Multimeter
02
Verify Signal with Noid Light

Check that ECM pulse reaches the connector. on the Mercedes-Benz GLC equipped with 2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC.

Required Tool: Noid Light
03
Replace Cylinder 4 Injector

Replace the faulty injector with OEM unit. on the Mercedes-Benz GLC equipped with 2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC.

Required Tool: Socket Set, O-ring Lube
04
Clear Codes and Test

Clear DTC memory and confirm smooth operation. on the Mercedes-Benz GLC equipped with 2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC.

Required Tool: OBD-II Scanner
Recommended Parts & Testing Tools

Equipment for Diagnosing Mercedes-Benz GLC (P0204)

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Direct-Fit Replacement Part

Mercedes-Benz GLC OEM Replacement Sensor

4.7 / 5.0 (Verified Fit)

Direct-fit replacement assembly engineered to OEM tolerances for Mercedes-Benz GLC.

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Sensor Signal Voltage Meter

AstroAI Auto-Ranging Digital Multimeter

4.6 / 5.0 (Best Seller)

Essential for testing 0.1V–5.0V sensor reference signals, ground continuity (<0.20Ω), and harness resistance.

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Top Mobile OBD-II Scanner

BlueDriver Bluetooth Pro OBDII Scan Tool

4.7 / 5.0 (50,000+ Reviews)

Reads and clears enhanced codes (ABS, Airbag, Transmission, Engine) & live freeze-frame telemetry on phone.

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Other Common Fault Codes on Mercedes-Benz GLC

Frequently diagnosed powertrain, emissions, and sensor trouble codes logged on the Mercedes-Benz GLC:

4. Mercedes-Benz GLC P0204 FAQs

What causes code P0204 to trigger on a Mercedes-Benz GLC?

On the Mercedes-Benz GLC (2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC), P0204 is most frequently caused by Faulty Cylinder 4 fuel injector or Broken wiring harness.

Where is the OBD-II port located on my Mercedes-Benz GLC?

On the Mercedes-Benz GLC, the 16-pin DLC diagnostic connector is located Driver lower kick panel near hood release lever. Plug in any standard OBD-II scanner with the ignition in the ON position to read freeze-frame parameters.

Can I safely drive my Mercedes-Benz GLC with code P0204?

No. Cylinder 4 is disabled, causing rough running and unburned fuel delivery issues. Given that P0204 carries a Critical severity rating, we advise avoiding heavy towing or aggressive throttle inputs until sensor readings are verified.