Guide to the Engine Camshaft Position Sensor for the 2010-2018 Mercedes-Benz C250
Fix check engine lights and poor running by choosing the right sensor for your C250's M271 engine.
- Stick with OEM supplier brands like Bosch, Hella, or Vemo for the best reliability on this German engine.
- Always inspect the electrical connector for oil contamination, a common failure point that can cause wider electrical issues.
- Replacement is a very simple DIY task requiring only basic tools and less than 30 minutes.
- A sensor fault code can sometimes be caused by a failing camshaft adjuster magnet, which is located nearby.
Symptoms of a Failing Camshaft Position Sensor
When a camshaft position sensor in your C250 starts to fail, the signals it sends to the engine computer become weak or incorrect. This can cause a range of noticeable problems. You should not ignore these signs, as they can worsen and potentially leave you stranded.
- Check Engine Light: This is the most common symptom. The ECU will detect a problem with the sensor's circuit and trigger a warning light. Common trouble codes include P0340 (Intake Camshaft Position Sensor 'A' Circuit) and P0365 (Exhaust 🎬 Watch: Understanding common camshaft sensor and adjuster fault codes. Camshaft Position Sensor 'B' Circuit).
- Rough Idle and Stalling: The engine may run unevenly, vibrate at a stop, or shut off unexpectedly.
- Difficulty Starting: A bad sensor can lead to long crank times, where the engine turns over for several seconds before starting. In some cases, it may not start at all.
- Reduced Engine Power and Poor Acceleration: Your car may feel sluggish or hesitate when you press the gas pedal because the engine timing is off.
Important: Check for Oil Leaks
A very common issue on the M271 engine is oil leaking through the camshaft position sensor and into the electrical connector. This oil can travel down the wiring harness, potentially damaging other components and even the main engine computer (ECU). When replacing a sensor, always inspect the connector for oil. If oil is present, clean it thoroughly with electrical contact cleaner. Mercedes-Benz has issued service information about this problem.
Choosing the Right Aftermarket Sensor
When it comes to electronic sensors for a Mercedes-Benz, quality matters significantly. While a low-priced part is tempting, a poor-quality sensor can fail quickly or provide inaccurate readings, bringing you right back to where you started. Here’s how to think about the available brands:
Tier 1: OEM Supplier & Premium Brands
These brands are either the original equipment manufacturer for Mercedes-Benz or are known for producing parts that meet or exceed OEM standards. They are the safest bet for reliability and longevity.
- Bosch: As a major OEM supplier for Mercedes-Benz, a Bosch sensor is often identical to the part you would get from the dealer, just in a different box. It is a top choice for fit and performance.
- Hella: Another German company with a strong reputation for quality electronics and sensors.
- Vemo: A well-regarded brand that specializes in European car parts and is known for quality.
Tier 2: Reputable Aftermarket Brands
These brands are known for producing reliable parts and offer a good balance between price and quality. They are a solid choice for most repairs.
- Delphi: A global parts manufacturer with a long history of producing quality electronic components.
- NGK/NTK: While famous for spark plugs, their sensor line is also well-respected.
- Standard Ignition (SMP): A long-standing company that produces reliable engine management parts.
- Walker Products: A trusted name in fuel system and engine management components.
Tier 3: Budget-Friendly Options
These brands offer the lowest prices but may have a higher risk of premature failure or inconsistent performance. They can be a viable option for a tight budget, but be aware of the potential trade-offs in longevity.
- Brands like Dorman, Facet, and other private-label store brands fall into this category. While they may function correctly, for a critical sensor on a German vehicle, it's often recommended to invest in a Tier 1 or Tier 2 brand to avoid doing the job twice.
A Note on Related Parts
Sometimes, a camshaft position sensor code is not caused by the sensor itself, but by a failing camshaft adjuster magnet (also called a solenoid). These magnets are located right next to the sensors and are also prone to failure and oil leaks. If you replace a sensor and the code returns, the adjuster magnet may be the actual culprit.
Cost to Replace a Camshaft Position Sensor
The cost can vary based on the part brand you choose and labor rates in your area. This is a very simple DIY job for most owners, which can save you money.
| Item | Estimated Cost |
|---|---|
| New Aftermarket Sensor | $22 - $102 |
| New OEM Sensor | $110 - $180 |
| Shop Labor | $70 - $140 |
| Total (DIY) | $22 - $102 |
| Total (Shop) | $92 - $242 |
Frequently Asked Questions
How many camshaft sensors does my C250 have?
The 1.8L M271 engine in the 2010-2018 C250 has two camshaft position sensors. One is for the intake camshaft and one is for the exhaust camshaft. They are located at the front of the engine.
Is this a difficult repair to do myself?
No, this is a very easy repair. The sensors are easily accessible at the front of the engine after removing the plastic engine cover. Each sensor is held in by a single E8 external Torx bolt and has one electrical connector. The job 🎬 Watch: Step-by-step guide to replacing the intake camshaft sensor. can be done in under 30 minutes 🎬 See this quick walkthrough for replacing both camshaft sensors. with basic tools.
Should I replace both sensors at the same time?
While not strictly necessary, it is often recommended. The sensors are the same age and have been exposed to the same conditions. If one has failed, the other may not be far behind. Given the low cost of the part and easy access, replacing them in pairs can be good preventative maintenance.
What happens if I don't replace a bad sensor?
You will continue to experience poor engine performance, bad fuel economy, and hard starting. Eventually, the sensor could fail completely, leaving you unable to start the car. More importantly, if the failure is accompanied by an oil leak into the harness, ignoring it can lead to much more expensive repairs to the wiring or engine computer.
Are there any recalls for this part?
There are no direct recalls for the camshaft position sensor itself. However, Mercedes-Benz did issue a warranty extension for the camshaft *adjusters* on MY 2012-2015 C250s to 10 years/120,000 miles, which can cause similar fault codes. There was also a recall on some 2015-2016 models for improperly welded camshafts, which is a more serious internal engine issue.
Helpful Videos
Technical Specifications
OEM Part Numbers: A2711500133 A0051531328 A0041539628
The M271 engine uses two sensors, one for the intake cam and one for the exhaust cam. They are held in by a single E8 external Torx bolt. The connector is a 3-pin rectangular plug.
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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 C250:
- 🎬 Helpful Videos
- 🛍️ Shop This Part
- Symptoms of a Failing Camshaft Position Sensor
- Important: Check for Oil Leaks
- Choosing the Right Aftermarket Sensor
- Tier 1: OEM Supplier & Premium Brands
- Tier 2: Reputable Aftermarket Brands
- Tier 3: Budget-Friendly Options
- A Note on Related Parts
- Cost to Replace a Camshaft Position Sensor
- Frequently Asked Questions
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