A Guide to the Engine Crankshaft Position Sensor for the 2007-2018 Mercedes-Benz CLS550
Understanding this critical engine sensor is key to preventing stalling and no-start problems in your CLS550.
- A failing crankshaft sensor is a common cause of no-start or stalling issues on the CLS550.
- Symptoms often appear when the engine is hot and may include a Check Engine Light with code P0335.
- For reliability, choose an OEM-equivalent brand like Bosch or a reputable aftermarket brand like Hella or Delphi.
- Replacement is a manageable DIY task for those with the right tools (especially an E8 Torx socket), but access is tight.
Is Your CLS550 Stalling or Not Starting? It Could Be the Crankshaft Sensor.
A failing crankshaft position sensor is a common issue on many Mercedes-Benz vehicles, including the CLS550. Because this sensor is so important for engine operation, its failure can cause major problems, from poor performance to leaving you stranded. The symptoms often get worse as the engine warms up, as heat can cause a failing sensor to stop working correctly. Recognizing the signs early can save you from a tow truck and more complex diagnostics.
Symptoms of a Failing Crankshaft Position Sensor
If your CLS550's crankshaft position sensor is going bad, you will likely notice one or more of the following issues:
- Engine cranks but won't start: This is the most common symptom. The starter will turn the engine over, but it won't fire up because the ECU isn't getting the signal it needs to start ignition and fuel delivery.
- Sudden stalling: The engine may shut off unexpectedly while driving, which can be very dangerous. This often happens after the engine has warmed up.
- Rough idle and engine vibration: The engine may shake or run unevenly when stopped at a light.
- Poor acceleration: You might feel a lack of power or a sluggish response when you press the gas pedal.
- Check Engine Light: A faulty sensor will almost always trigger the Check Engine Light and store a diagnostic trouble code, most commonly P0335.
Generation and Engine Differences
The 2007-2018 CLS550 was built with two different V8 engines. The 2007-2011 models (C219 chassis) have the 5.5L M273 engine. The 2012-2018 models (C218 chassis) have the 4.7L twin-turbo M278 engine. The location of the crankshaft position sensor is on the driver's side of the engine near the transmission bell housing on both, but access can vary. Always confirm the part fits your specific year and engine.
Choosing the Right Aftermarket Sensor: Quality Matters
When it comes to critical electronic sensors on a Mercedes-Benz, quality is extremely important. While a cheap, unbranded sensor might save you money initially, it can fail quickly, leaving you with the same problem. For a part this essential, it is strongly recommended to choose a brand known for quality.
Brand Quality Tiers
- Tier 1: OEM-Equivalent Brands (e.g., Bosch, Hella): Bosch is a well-known original equipment manufacturer (OEM) for Mercedes-Benz. Choosing a Bosch sensor is the closest you can get to buying the part from a Mercedes dealer. Hella is another German brand with a strong reputation for quality electronics. These brands are highly recommended for reliability.
- Tier 2: Reputable Aftermarket Brands (e.g., Delphi, NGK/NTK, Standard Ignition/Intermotor, Vemo): These are established companies that produce reliable parts. Delphi and NGK (under their NTK sensor brand) are often OEM suppliers for other car manufacturers and produce quality components. They offer a good balance of price and quality.
- Tier 3: Budget Brands (e.g., Walker, Facet, True Tech, etc.): While these brands offer the lowest prices, their long-term reliability can be a gamble. For a critical sensor like this, it's generally best to invest in a Tier 1 or Tier 2 brand to avoid having to do the job twice.
Pro Tip: Many owners and mechanics strongly advise against using the cheapest available sensor for a Mercedes-Benz. The labor to replace the part often costs more than the part itself, so using a quality sensor from a brand like Bosch can prevent future headaches.
Cost to Replace the Crankshaft Position Sensor
| Item | Estimated Cost |
|---|---|
| New Aftermarket Part | $24.74 - $108.98 |
| Shop Labor | $98 - $143 |
| Total Estimated Cost (Aftermarket) | $123 - $252 |
Note: Costs are estimates and can vary based on your location and the specific repair shop.
Frequently Asked Questions (FAQ)
Is there a recall on the CLS550 crankshaft position sensor?
No, there are no specific recalls for the crankshaft position sensor on the 2007-2018 CLS550. A search of the NHTSA database found a recall for this sensor on some 2006-2008 Mercedes models with diesel engines, which does not apply to the gas-powered CLS550. Always check for recalls using your vehicle's specific VIN on the NHTSA or Mercedes-Benz websites.
Where is the crankshaft position sensor located on the CLS550?
The sensor is located on the driver's side of the engine, at the back, where the engine meets the transmission. It is held in by a single E8 external Torx bolt. Access is tight, and it may require removing the air intake ducting and working with extensions and a swivel socket.
Can I replace this sensor myself?
Yes, this is a feasible DIY job for someone with moderate mechanical skill and the right tools. The main challenge is the tight access to the sensor's location. You will need a ratchet, extensions, a swivel, and an E8 external Torx socket. The job must be done when the engine is cold to avoid burns.
Should I buy an OEM or aftermarket sensor?
For this specific part on a Mercedes-Benz, an OEM-equivalent brand like Bosch is highly recommended for reliability. While less expensive aftermarket options exist, a failure of this sensor can leave you stranded. Investing in a quality part is a wise choice to ensure long-term performance and avoid repeat repairs.
What happens if I don't replace a bad crankshaft sensor?
Ignoring a failing crankshaft position sensor will lead to worsening symptoms. You will experience more frequent stalling, rough running, and poor fuel economy. Eventually, the sensor will fail completely, and your car will not start at all, potentially leaving you stranded.
Helpful Videos
![Fixing a Mercedes ML350 (2006) P0335 Code | Crankshaft Sensor & ECU Drama! [First MB Diagnostic]](https://img.youtube.com/vi/a_wNhpU85to/mqdefault.jpg)
Technical Specifications
OEM Part Numbers: A2729050000 6429050000 A6429050000 2729050000
The sensor is a Hall effect or inductive sensor that reads the position of the crankshaft from the flywheel/reluctor wheel. It is secured by one E8 external Torx bolt and has a 3-pin electrical connector.
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Mercedes-Benz CLS550:
- 🎬 Helpful Videos
- 🛍️ Shop This Part
- Is Your CLS550 Stalling or Not Starting? It Could Be the Crankshaft Sensor.
- Symptoms of a Failing Crankshaft Position Sensor
- Generation and Engine Differences
- Choosing the Right Aftermarket Sensor: Quality Matters
- Brand Quality Tiers
- Cost to Replace the Crankshaft Position Sensor
- Frequently Asked Questions (FAQ)
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