P0351 Mercedes-Benz Code - Ignition Coil 1 Primary/Secondary Circuit Malfunction
Quick Answer
The ignition system on the vehicle uses individual ignition coils for each cylinder. Common causes include Faulty Ignition Coil 1, Ignition Coil 1 harness is open or shorted, Ignition Coil 1 circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P0351 Mercedes-Benz indicates Ignition Coil 1 Primary/Secondary Circuit Malfunction.
- Common causes
- Common causes include Faulty Ignition Coil 1, Ignition Coil 1 harness is open or shorted, Ignition Coil 1 circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P0351 Mercedes-Benz Description
What are the Possible Causes of the DTC P0351 Mercedes-Benz?
- Faulty Ignition Coil 1
- Ignition Coil 1 harness is open or shorted
- Ignition Coil 1 circuit poor electrical connection
- Faulty Engine Control Module (ECM)
How to Fix the DTC P0351 Mercedes-Benz?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0351 Mercedes-Benz code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
Need more information about the P0351 Mercedes-Benz code?
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Frequently Asked Questions about P0351 Mercedes-Benz Code
1. What are the common symptoms of OBDII code P0351 in a Mercedes-Benz?
- Common symptoms include engine misfiring, rough idle, loss of power, and illuminated check engine light.
2. What can cause the ignition coil 1 primary/secondary circuit malfunction in a Mercedes-Benz?
- Possible causes include a faulty ignition coil, damaged wiring or connectors, a defective spark plug, or issues with the engine control module.
3. How can I diagnose the P0351 code in my Mercedes-Benz?
- To diagnose the code, you can use an OBDII scanner to read the code, visually inspect the ignition coil and related components, check for damaged wires, and perform a continuity test.
4. Can I continue driving my Mercedes-Benz with the P0351 code?
- It is not recommended to drive your vehicle with the P0351 code as it can lead to further damage to the engine and other components.
5. How do I repair the ignition coil 1 primary/secondary circuit malfunction in my Mercedes-Benz?
- The repair usually involves replacing the faulty ignition coil, repairing or replacing damaged wiring, checking and replacing spark plugs, and clearing the code with an OBDII scanner.
6. Are there any preventive measures to avoid the P0351 code in a Mercedes-Benz?
- Regular maintenance, such as checking and replacing spark plugs and ignition coils at recommended intervals, can help prevent the occurrence of the P0351 code.
7. Can a DIY enthusiast fix the P0351 code in a Mercedes-Benz?
- Depending on your skill level and access to tools, a DIY enthusiast may be able to replace the ignition coil or spark plugs themselves. However, more complex diagnostics and repairs may require professional help.
8. Is it necessary to reset the ECU after repairing the P0351 code in a Mercedes-Benz?
- It is recommended to reset the ECU after repairing the P0351 code to clear the fault code memory and ensure proper functioning of the vehicle.
9. How long does it typically take to repair the ignition coil 1 primary/secondary circuit malfunction in a Mercedes-Benz?
- The repair time can vary depending on the extent of the issue and the availability of parts, but it usually takes a few hours to complete the repair.
10. What should I do if the P0351 code reappears after repairs in my Mercedes-Benz?
- If the code reappears after repairs, it is recommended to recheck the ignition coil, wiring, and related components for any issues that may not have been addressed during the initial repair.
Discuss the causes and fixes for P0351 Mercedes-Benz OBDII Code
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I have one MB CLS550 2007 the check engine light came on with this code right after I change the coil on it but the engine runs and drives perfect without any issue. I clear the code but once you turn the car on and off the check engine light coming back on. I want to see what are the possibilities before I start spending money on it
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Sam I have the same model car and same exact issue, I replaced the coil pack and the harness connector and the code still comes back.
Did you figure out the problem?
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Hey Adam,
With code P0351 (“Ignition Coil 1 Primary/Secondary Circuit Malfunction”), here’s what I’d check based on having the same symptoms even after replacing the coil and the connector:
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Make sure the coil’s ground is solid. Even a tiny bit of corrosion or loose ground can let everything seem fine but trigger that code.
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Inspect the spark plug and boot for cylinder #1. If the spark plug is fouled, or the boot is cracked, or there’s oil/water in the plug well, that may cause a misread from the coil.
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Try swapping coil #1 with coil #2 (for example). If after swapping, the error goes to cylinder 2, then the coil was bad. If it stays on cylinder 1, the issue is likely wiring or ECM.
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Examine all wiring from coil #1 back to the ECM. Look for breaks, shorts, melted insulation, or damage from heat/vibration.
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If all the above checks out good (coil okay, wiring okay, plug/boot okay), then the coil driver inside the ECM is a suspect. That’s a tougher job to fix and might mean replacing or repairing the ECM.
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Other than the Ignition Coil 1 I have not seen any other component triggering the P0351 code. Probably was just coincidence.
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Hi Sam, did you ever figured out how to fix your check engine light problem? I have a MB C300 2010 and having the exact same problem as you; not sure what to do next.
Thanks,-
I’m having the same exact issue I changed the coil and the code comes back? How did you resolve your problem? Was it the ECM?
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