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P0172 on Mercedes-Benz GLC: Fix & DLC Location

Factory diagnostic troubleshooting wire for fault code P0172 (System Too Rich (Bank 1) - Symptoms, Causes & Step-by-Step Fix) specifically on the Mercedes-Benz GLC (2020–2026, 2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC).

2020–2026
GLCSUV
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
Drivable (Short Trip)
Medium urgency level
Est. DIY Time
45 – 90 Min
Basic hand tools
Check P0172 On Another Mercedes-Benz Model:

1. Symptoms of P0172 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 P0172, drivers commonly observe:

Check Engine Light on on Mercedes-Benz GLC (2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC)
Strong unburnt fuel odor from exhaust on Mercedes-Benz GLC (2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC)
Black carbon soot around exhaust tip on Mercedes-Benz GLC (2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC)
Rough idle and engine bogging under throttle on Mercedes-Benz GLC (2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC)
Noticeable drop in MPG 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 or leaking fuel injector (Mercedes-Benz OEM Part)
25%
Contaminated Mass Air Flow (MAF) sensor (Mercedes-Benz OEM Part)
12%
Stuck closed EVAP canister purge valve (Mercedes-Benz OEM Part)
8%
Excessive fuel pressure regulator failure (Mercedes-Benz OEM Part)

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

01
Clean MAF Sensor and Throttle Body

Use dedicated MAF cleaner to remove carbon buildup from sensor wires. on the Mercedes-Benz GLC equipped with 2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC.

02
Check Short Term & Long Term Fuel Trims

Use live OBD-II scanner data; negative trims beyond -10% indicate the ECU is cutting fuel. on the Mercedes-Benz GLC equipped with 2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC.

03
Inspect Fuel Injector Leak-Down

Perform a fuel pressure leak-down test to identify injectors leaking raw gasoline into cylinders while parked. on the Mercedes-Benz GLC equipped with 2.0L Turbo 4-Cyl with EQ Boost (255HP) / AMG GLC 43 4MATIC.

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 P0172 FAQs

What causes code P0172 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), P0172 is most frequently caused by Faulty or leaking fuel injector or Contaminated Mass Air Flow (MAF) sensor.

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 P0172?

Driveable short distances, but unburnt fuel can damage catalytic converters. Given that P0172 carries a Medium severity rating, we advise avoiding heavy towing or aggressive throttle inputs until sensor readings are verified.