1. What is P2112 in Mercedes E-Class?

The P2112 OBD-II code stands for Throttle Actuator Control System - Forced Closed. For the Mercedes-Benz E-Class W213 (2019-2024)—a flagship European luxury sedan—this code targets the electronic throttle body (ETB) in its 2.0T M264 engine, standard in E300 L, E300 L 4MATIC, and AMG E53 trims (paired with 9-speed 9G-TRONIC transmission).

The E300 L’s ETB regulates air flow into the engine (replacing mechanical cables) via two electric motors and position sensors. The ECU sends signals to open/close the throttle plate (10–90% range) based on driver input. P2112 triggers when the ECU detects the throttle plate is stuck closed (≤5% opening) despite commands to open—caused by carbon buildup, motor failure, or sensor malfunctions.

Mercedes E300 L Specific Note: This code is widespread in 2020-2023 E300 L 4MATIC models, per Mercedes Technical Service Bulletin (TSB) 22-10-03. The M264’s direct injection system produces excess carbon, which accumulates on the throttle plate; stop-and-go urban driving worsens buildup, forcing the plate closed.

2. Common Causes of P2112 in 2019-2024 E300 L

P2112 in Mercedes E300 L M264 models stems from electronic throttle body failures—below are real-world cases diagnosed with the ICARZONE UR800:

• Carbon Buildup on Throttle Plate (2021 E300 L 4MATIC): An owner with 65,000 miles reported sudden power loss. The UR800’s Throttle Plate Position Test showed 3% opening (ECU command: 30%). Cleaning the plate with throttle body cleaner (#CRC 05078) fixed P2112 (per TSB 22-10-03).
• Throttle Body Motor Failure (2020 E300 L Luxury): A Luxury trim owner’s P2112 reappeared after cleaning. The UR800’s Motor Voltage Test showed 0V to the ETB motor (normal: 11–14V). Replacing the throttle body with OEM #2721410401 resolved the issue.
• Position Sensor Malfunction (2019 AMG E53): An AMG owner’s P2112 occurred during hard acceleration. The UR800’s Sensor Calibration Test found a 15% mismatch between actual and reported plate position. Recalibrating the sensor via UR800’s "Throttle Learn" tool cleared the fault.
• ECU Firmware Gap (2022 E300 L): A 2022 E300 L owner’s P2112 triggered after a software update. The UR800’s Firmware Check showed version 4.2.0 (latest: 4.5.1). Updating the ECU via UR800 fixed command communication with the ETB.

3. Key Symptoms of P2112 in E300 L M264

P2112 symptoms in the Mercedes E300 L focus on throttle restriction and engine performance—watch for these signs that signal a stuck closed throttle body:

4. Mercedes E-Class Trims/Engines Prone to P2112

Mercedes service data highlights these 2019-2024 E-Class configurations with the highest P2112 occurrence rates (all M264/M177 engines):

5. Diagnose P2112 with ICARZONE UR800

Diagnose P2112 in your Mercedes E300 L M264 accurately with the UR800’s Mercedes-specific throttle tools. Follow these steps (engine off, key in "ON" position; ensure battery voltage is 12.4–12.7V):

Case Example: A 2021 E300 L 4MATIC failed Step 2 (2% position) and Step 5 (TSB 22-10-03 eligible). The UR800’s Component Location Tool guided ETB access (top of engine, intake manifold). Cleaning the throttle plate restored position to 31%—P2112 cleared, and power loss was resolved.

6. How to Fix P2112 in Mercedes E300 L

Resolve P2112 in your E300 L with these UR800-verified solutions—tailored to the M264 engine’s electronic throttle system:

1. Clean Electronic Throttle Body (Most Common Fix for TSB 22-10-03)

1. Confirm buildup via UR800’s Step 2. Disconnect the negative battery terminal and remove the engine cover (4 Torx T30 screws).
2. Locate the ETB: Mounted on the intake manifold (driver’s side), connected to the air intake hose (1 clamp + 4 10mm bolts).
3. Remove the air intake hose (loosen clamp with flathead screwdriver) and disconnect the ETB’s 6-pin electrical connector (press release tab).
4. Remove the 4 ETB mounting bolts and pull the unit off the manifold. Use a flashlight to inspect the plate—scrape loose carbon with a plastic scraper (avoid metal to prevent damage).
5. Spray throttle body cleaner (#CRC 05078) on a microfiber cloth and wipe the plate and bore until clean. Let dry 10 minutes, then reinstall the ETB (torque bolts to 8 ft-lbs).
6. Reconnect the connector and air hose, then reattach the battery. Use UR800’s "Throttle Learn" tool to recalibrate the plate position. Clear P2112 and test drive—verify smooth acceleration.

2. Replace Electronic Throttle Body (for Motor Failure)

1. Confirm motor failure via UR800’s Step 3. Follow Steps 1–3 above to remove the old ETB.
2. Install an OEM electronic throttle body:
   • 2019-2021 E300 L: #2721410401
   • 2022-2024 E300 L: #2721410801 (updated motor design)
   Do not reuse old gaskets—install a new OEM gasket (#2721410501).
3. Reattach the ETB to the manifold (torque bolts to 8 ft-lbs), reconnect the electrical connector and air hose.
4. Reconnect the battery and use UR800 to perform "Throttle Adaptation" (follows on-screen prompts to calibrate new ETB).
5. Clear P2112 with UR800 and run a road test—accelerate from 0–60 MPH to confirm no power loss or hesitation.

3. Update ECU Firmware (for Communication Gaps)

1. Confirm firmware issue via UR800’s Step 5. Connect UR800 to the E300 L’s OBD-II port (under steering wheel) and turn key to "ON."
2. Select "Mercedes-Benz" > "E-Class W213" > "M264 2.0T" > "ECU" > "Firmware Update." The tool will detect the current version and download the latest (v4.5.1 for 2022+ models).
3. Do not turn off the key or disconnect UR800 during the update (takes 25–30 minutes). The tool will alert you when complete (ECU reboots automatically).
4. Run UR800’s Step 2 (plate position test) to confirm 28–32% opening. Clear P2112 and verify throttle response with a test drive.

7. P2112 Repair Costs & Maintenance Tips

P2112 repair costs for the Mercedes E300 L M264 vary by cause. Use this table to budget:

Maintenance Tips for Mercedes E300 L Owners

• E300 L 4MATIC (urban drivers): Clean the throttle body every 30,000 miles (preventive) — use #CRC 05078 cleaner and replace the gasket to avoid TSB 22-10-03 buildup.
• Use Top Tier detergent gasoline (91+ octane)—low-quality fuel increases carbon deposits on the throttle plate (worsens P2112 risk).
• Perform monthly "high-speed" drives (60+ MPH for 10 minutes)—helps burn off mild carbon buildup before it sticks the throttle closed.
• Update ECU firmware via UR800 after Mercedes software updates—prevents communication gaps with the ETB (critical for 2022+ models).
• Perform the UR800’s Throttle System Health Check every 15,000 miles — monitor plate position and motor voltage to catch issues before P2112 triggers.

8. Mercedes E-Class-Specific FAQs