1. What is P0097 in Mercedes-Benz GLC 300?

The P0097 OBD-II code stands for Fuel Pressure Regulator Control Circuit High. For the Mercedes-Benz GLC 300 (2018-2024)—a top-selling European luxury compact SUV—this code targets the electronic fuel pressure regulator (EFR) in its 2.0T turbo engines: the M274 (2018-2020) and M254 (2021-2024), standard in GLC 300 and GLC 300 4MATIC trims.

The GLC 300’s EFR controls fuel pressure (target: 50–55 psi at idle) to optimize combustion, critical for meeting EU6 emissions standards and maintaining 24–30 MPG highway efficiency. The regulator receives voltage signals from the ECU (Engine Control Unit) to adjust pressure; P0097 triggers when the ECU detects excessively high voltage (>5V) in the EFR’s control circuit. This signals a faulty regulator, damaged wiring, or ECU driver failure—all of which disrupt fuel delivery and engine performance.

Mercedes GLC 300 Specific Note: This code is widespread in 2019-2023 GLC 300 models, per Mercedes Technical Service Bulletin (TSB) 21-12-03. The M274/M254 engines’ direct injection system places high stress on the EFR; frequent short trips or low-quality fuel accelerate wear, leading to circuit overvoltage.

2. Common Causes of P0097 in 2018-2024 GLC 300

P0097 in Mercedes GLC 300 2.0T models stems from fuel pressure regulator circuit overvoltage—below are real-world cases diagnosed with the ICARZONE MA200 V6:

• Faulty Electronic Fuel Pressure Regulator (2020 GLC 300 4MATIC): An owner with 62,000 miles reported rough acceleration and a "Check Engine" light. The MA200 V6’s Fuel Pressure Regulator Voltage Test showed 6.8V (normal: 0.5–5V). Replacing the EFR with OEM #A0000780347 (per TSB 21-12-03) fixed P0097.
• Shorted Wiring (2019 GLC 300): A GLC 300 owner’s P0097 reappeared after EFR replacement. The MA200 V6’s Circuit Continuity Test found a short between the EFR’s signal wire and battery positive (insulation damaged by engine heat). Repairing with heat-resistant wire (#Dorman 10501) resolved the overvoltage.
• ECU Driver Failure (2018 GLC 300 4MATIC): An owner’s P0097 persisted after wiring repairs. The MA200 V6’s ECU Output Test confirmed the EFR driver circuit was sending 7.2V (instead of 3–5V). Updating the ECU firmware (v2.6.0) via MA200 V6 (addressed in TSB 22-09-04) fixed voltage regulation.
• Clogged Fuel Filter (2021 GLC 300): An owner’s P0097 occurred after refueling with low-quality gasoline. The MA200 V6’s Fuel Pressure Test showed 38 psi (below target 50 psi)—the filter’s restriction forced the EFR to overwork, causing circuit voltage spikes. Replacing the in-tank filter (#A0004770893) stabilized pressure and cleared P0097.

3. Key Symptoms of P0097 in GLC 300 2.0T

P0097 symptoms in the Mercedes GLC 300 focus on fuel delivery and performance—watch for these signs that signal EFR circuit overvoltage:

4. Mercedes GLC 300 Trims/Engines Prone to P0097

Mercedes service data highlights these 2018-2024 GLC 300 configurations with the highest P0097 occurrence rates (all 2.0T engines):

5. Diagnose P0097 with ICARZONE MA200 V6

Diagnose P0097 in your Mercedes GLC 300 2.0T accurately with the MA200 V6’s Mercedes-specific fuel system tools. Follow these steps (engine off, key in "ON" position):

Case Example: A 2020 GLC 300 4MATIC failed Step 2 (6.5V) and Step 5 (TSB 21-12-03 eligible). The MA200 V6’s Component Location Tool guided EFR access (engine left side, near fuel rail). Replacing the EFR fixed P0097—verified by test drive (smooth acceleration, restored MPG to 27 highway).

6. How to Fix P0097 in Mercedes GLC 300

Resolve P0097 in your GLC 300 with these MA200 V6-verified solutions—tailored to the M274/M254 engine’s fuel system:

1. Replace Electronic Fuel Pressure Regulator (Most Common Fix for TSB 21-12-03)

1. Confirm EFR failure via MA200 V6’s Step 2. Disconnect the negative battery terminal and relieve fuel pressure (remove fuel pump fuse F32, start engine until it stalls).
2. Locate the EFR: Mounted on the left side of the engine, near the fuel rail (3-pin electrical connector, 1 mounting bolt).
3. Disconnect the EFR’s electrical connector (press the release tab) and remove the mounting bolt (8mm socket).
4. Pull the old EFR straight out—note the O-ring seal (replace if damaged). Install an OEM EFR:
   • 2018-2020 GLC 300 (M274): #A0000780347
   • 2021-2024 GLC 300 (M254): #A0000781547 (updated pressure sensor)
   Lubricate the new O-ring with clean engine oil.
5. Reinstall the mounting bolt (torque to 89 in-lbs), reconnect the electrical connector, and replace the fuel pump fuse. Clear P0097 with MA200 V6 and test drive—verify fuel pressure stays 50–55 psi at idle.

2. Repair Shorted/Damaged Wiring

1. Confirm wiring short via MA200 V6’s Step 4. Trace the EFR’s signal wire from the regulator to the ECU (runs along the engine harness, left side).
2. Identify damaged sections (melted insulation, frays) and cut out 1 inch on each side of the fault with wire cutters.
3. Splice new heat-resistant 18-gauge automotive wire (#Dorman 10501) using heat-shrink butt connectors—crimp connectors and apply heat to seal the shrink tube.
4. Secure the repaired harness to the engine bay with heat-resistant zip ties (avoids contact with hot components). Reconnect the EFR and ECU connectors.
5. Retest EFR voltage with MA200 V6 (Step 2) and clear P0097. Test drive to confirm no voltage spikes during acceleration.

3. Replace Clogged Fuel Filter

1. Confirm low pressure via MA200 V6’s Step 3. Remove the rear seat cushion to access the fuel pump assembly (under the left seat).
2. Disconnect the fuel pump’s electrical connector and fuel lines (use a fuel line disconnect tool to avoid damage).
3. Remove the fuel pump assembly (turn the locking ring counterclockwise) and extract the in-tank filter (attached to the pump inlet).
4. Install an OEM fuel filter:
   • All 2018-2024 GLC 300: #A0004770893
   Replace the fuel pump gasket if cracked.
5. Reinstall the fuel pump assembly, reconnect lines/electrical, and restore fuel pressure. Retest pressure with MA200 V6 and clear P0097.

7. P0097 Repair Costs & Maintenance Tips

P0097 repair costs for the Mercedes GLC 300 2.0T vary by cause. Use this table to budget:

Maintenance Tips for Mercedes GLC 300 Owners

• GLC 300 4MATIC (urban drivers): Replace the EFR every 75,000 miles (preventive) — use OEM #A0000781547 for 2021+ models to avoid TSB 21-12-03 wear.
• Refuel only with Top Tier detergent gasoline (91+ octane) — low-quality fuel clogs filters and degrades the EFR’s pressure sensor.
• Replace the in-tank fuel filter every 40,000 miles — a clogged filter forces the EFR to overwork, leading to circuit overvoltage.
• Inspect the EFR wiring during oil changes—wrap exposed sections with heat-resistant tape (#3M 33+) to protect against engine heat.
• Perform the MA200 V6’s Fuel System Health Check every 15,000 miles — monitor EFR voltage and fuel pressure to catch issues before P0097 triggers.

8. Mercedes GLC 300-Specific FAQs