1. What is P0413 in Mercedes C-Class?

The P0413 OBD-II code stands for Secondary Air Injection (SAI) System Circuit High Input (Bank 1). For the Mercedes-Benz C-Class W206 (2022-2024)—a leading European luxury sedan with global commuter and executive demand—it targets the SAI system’s control circuit in its M254 2.0T turbocharged engine, standard in C300, C350e PHEV, and C43 AMG trims (paired with 9G-TRONIC automatic transmission).

The M254’s SAI system reduces cold-start emissions by injecting fresh air into the exhaust manifold, accelerating catalytic converter light-off. It relies on an air pump (#2239050100), solenoid valve (#2239050200), and relay (#0005458705) controlled by the ECU. P0413 triggers when the ECU detects a persistent voltage above 4.8V in the SAI circuit for 5+ seconds, indicating a faulty relay, shorted wiring, failed solenoid, or ECU communication error that disrupts air injection.

Mercedes C-Class Specific Note: This code is widespread in 2022-2023 C300 models, per Mercedes-Benz Technical Service Bulletin (TSB) 27-10-04. The M254’s SAI relay uses a solid-state design prone to overheating from frequent cold starts—short trips and urban driving increase relay load, causing circuit high voltage and triggering P0413.

2. Common Causes of P0413 in 2022-2024 C-Class

P0413 in Mercedes C-Class M254 models stems from SAI circuit or component issues—below are real-world cases (and customer feedback) diagnosed with the ICARZONE UR800:

• SAI Relay Failure (2023 C300): An owner with 42,000 miles reported cold-start rough idle and check engine light. The UR800’s SAI Circuit Voltage Test showed 5.1V (normal: 12V switch signal). Replacing the relay (#0005458705) per TSB 27-10-04 fixed P0413.
• SAI Wiring Short (2024 C43 AMG): A 2024 C43 owner’s P0413 reappeared after engine bay service. The UR800’s Circuit Continuity Test detected a short (0Ω resistance) in the solenoid wiring. Repairing frayed wires near the exhaust manifold resolved the issue.
• SAI Solenoid Valve Failure (2022 C350e PHEV): A 2022 C350e owner’s P0413 triggered with reduced electric mode range. The UR800’s Solenoid Activation Test showed no response. Replacing the solenoid (#2239050200) restored circuit voltage and fixed P0413.
• ECU Communication Fault (2022 C300 4MATIC): A 2022 C300 owner’s P0413 occurred after a software update. The UR800’s ECU Signal Test confirmed poor communication. Reflashing the ECU with Mercedes’ latest firmware resolved the issue.

3. Key Symptoms of P0413 in M254 Engine

P0413 symptoms in the Mercedes C-Class focus on SAI system performance and emission control—watch for these signs of circuit high input:

4. C-Class Trims/Engines Prone to P0413

Mercedes service data highlights these 2022-2024 C-Class configurations with the highest P0413 occurrence rates (all M254 2.0T engines):

5. Diagnose P0413 with ICARZONE UR800

Diagnose P0413 in your Mercedes C-Class M254 accurately with the UR800’s Mercedes-specific emission tools. Follow these steps (engine cold; battery voltage 12.4–12.7V):

Case Example: A 2023 C300 4MATIC failed Step 2 (5.2V) and Step 5 (TSB 27-10-04 eligible). The UR800’s Component Location Tool guided relay access (engine bay fuse box, slot K19). Replacing the worn relay restored voltage to 12V—P0413 cleared, and cold-start rough idle ceased.

6. How to Fix P0413 in Mercedes-Benz C-Class

Resolve P0413 in your C-Class with these UR800-verified solutions—tailored to the M254 engine’s SAI system:

1. Replace SAI Relay – Most Common Fix for TSB 27-10-04

1. Confirm relay failure via UR800’s Step 2. Disconnect the negative battery terminal and locate the engine bay fuse box (driver-side).
2. Open the fuse box cover (release clips) and identify the SAI relay (labeled "SAI" or slot K19).
3. Pull the old relay from the socket (use pliers if tight) and insert an OEM replacement (#0005458705).
4. Close the fuse box cover and reconnect the battery. Use UR800 to retest SAI circuit voltage.
5. Clear P0413 and test drive—confirm smooth cold starts and stable circuit voltage.

2. Repair SAI Wiring Short

1. Confirm wiring issue via UR800’s Step 3. Trace the SAI wiring from the relay/solenoid to the ECU (passenger-side firewall).
2. Identify frayed or damaged sections (common near exhaust manifold brackets). Cut the faulty segment (wire cutters) and strip 1/4 inch of insulation.
3. Splice with heat-shrink connectors (#Dorman 84715) rated for high temperatures (engine bay reaches 300°F+).
4. Crimp connectors and apply heat to seal. Wrap the repaired section with heat-resistant glass cloth tape (#3M 2166).
5. Secure wiring to the chassis with anti-vibration clips. Reconnect the relay/solenoid connector. Use UR800 to retest continuity (0.5–1Ω). Clear P0413 and test drive.

3. Replace SAI Solenoid Valve

1. Confirm solenoid failure via UR800’s Step 4. Locate the solenoid (attached to the SAI air pump, front of engine bay).
2. Disconnect the electrical connector and air hoses (use pliers to loosen clamps).
3. Remove the solenoid mounting bolts (2 x 10mm socket wrench) and extract the old unit.
4. Install an OEM solenoid (#2239050200) and torque bolts to 10 ft-lbs. Reconnect hoses and electrical connector.
5. Use UR800 to perform a "SAI System Adaptation" reset. Clear P0413 and test drive—verify solenoid activation via live data.

7. P0413 Repair Costs & Maintenance Tips

P0413 repair costs for the Mercedes C-Class M254 vary by cause. Use this table to budget for SAI system issues:

Maintenance Tips for C-Class Owners

• C300 4MATIC (2022-2023): Replace SAI relay every 45,000 miles (preventive) — use OEM #0005458705 to comply with TSB 27-10-04 and avoid P0413.
• Cold-weather owners: Run the engine for 5+ minutes after cold starts to reduce SAI relay heat buildup.
• Inspect SAI wiring every 30,000 miles—secure loose harnesses near exhaust components to prevent abrasion.
• C350e PHEV owners: Use gasoline mode for 30 minutes monthly to keep SAI components active.
• Perform the UR800’s SAI System Health Check every 15,000 miles — monitor voltage, relay activation, and solenoid response to catch issues before P0413 triggers.

8. C-Class-Specific FAQs