Problems with the Crankshaft Position Sensor (CPS) on Mercedes-Benz cars are common. If you have been experiencing stalling or no-start conditions, a failed crankshaft position sensor is often the problem. If the engine cranks, your CPS may have failed, but it will not start. At first, you may experience no-start conditions intermittently. As the crankshaft position sensor fails, the car will no longer start or will die when you are driving. Starting problems are initially random but more frequent when the engine is hot. Other symptoms of a failed crankshaft position sensor are poor acceleration, engine vibrations, poor throttle response, bad fuel economy, hesitation, and engine stalls. The engine starts if you let it cool down. If you are stuck in a parking lot, and the car will not start, let the car cool down for at least 30 minutes and then try again.
Replacing the crankshaft position sensor is easy, do it yourself project. Replacing the CPS sensor may fix the crank and no-start conditions. To perform this repair yourself, follow the step-by-step instructions provided below. Completing this repair yourself costs under $80 vs. $400 at a shop. You will need one to two hours to make this repair if you are performing this job for the first time.
How to replace the crankshaft position sensor on a Mercedes-Benz
This repair guide will show you how to replace the CPS yourself. The crankshaft position on most Mercedes-Benz cars, such as E320, C240, S430, and S500, is located at the back of the engine by the flywheel housing in front of the firewall. It monitors the engine crankshaft position and speed and is one of the most important input sensors used by the Engine Control Unit (ECU).
Here is a list of tools to change the CPS on your Mercedes-Benz. We have provided links to Amazon products if you need these tools.
- Female Torx Socket Set
- 3/8 Rachet Wrench
- 6-inch 3/8 ratchet extension An even better option would be a flexible ratchet extension.
- 3/8 universal joint
A new crankshaft position sensor can be ordered on Amazon for under $50. Make sure to enter the year and model of your Mercedes-Benz to get the correct fit.
Remove the engine cover. Disconnect the two air tubes from the engine cover. Grab the engine cover and lift it. There are no screws that hold the engine cover in place, only four clips.
Locate the crankshaft position sensor (CPS) on the driver’s side, towards the rear of the engine, back of the engine, and near the firewall.
Unplug the electrical connector from the CPS sensor. Squeeze the connector and pull it away from the CPS sensor.
Remove bolt. Remove the crankshaft position sensor. An E8 or E10 bolt will hold the CPS sensor in place.
Install new sensor. Place the new sensor in the crankshaft position sensor hole and hand tighten the bolt. Once you can no longer hand-tighten the bolt, use the 3/8 ratchet to tighten the bolt. Torque the bolt to about 10Nm. or 7 ft-lb if you have a 3/8 torque wrench.
Connect the electrical connector to the new Crankshaft Position Sensor. Push the electrical connector to the CPS end until it snaps into place.
Reinstall the engine cover. Place the engine cover back on top of the engine. Make sure that the engine cover is not loose.
Symptoms of a defective crankshaft position sensor on a Mercedes-Benz
Engine Cranks but no Start, Dies, Stalls, or Backfires
A failed crankshaft position sensor can cause your engine to stall or not start at all. Your Mercedes-Benz may start and run briefly or until it gets warm and dies. The engine may crank, but it will not start. You may need to crank the engine longer to get it to start.
The failed crankshaft position sensor can also impact the idling, acceleration, or transmission shifting. Sometimes, it can cause your transmission to go into limp mode. You may also notice an increase in engine vibrations.
Check engine light
The check engine light is usually illuminated on your instrument cluster. You can easily use a $20 scanner to read the fault code, explaining why the check engine light is on. When the CPS is malfunctioning, the engine control module will trigger a fault code if it does not receive any signal from the CPS.
Fault codes related to the crankshaft position sensor are:
- P0335 Crankshaft Position Sensor A Circuit Malfunction
- P0336 Crankshaft Position Sensor A Circuit Range / Performance
- P0337 Crankshaft Position Sensor A Circuit Low Input
- P0338 Crankshaft Position Sensor A Circuit High Input
- P0339 Crankshaft Position Sensor A Circuit Intermittent
- P0385, P0386, P0387, P0388 P0389 are related to B Circuit.
- P1336 is usually related to a wiring problem, air gap, flywheel ring gear damage, and CPS sensor.
Ignition Malfunction / Stall / No Start
If the crankshaft position sensor fails, it will not send information about the crankshaft’s position and speed of the engine RPMs to the ECU. As a result, the ECU doesn’t know when to send the spark plugs and how to adjust the fuel mixture. This can cause your car to stall or hesitate to start. If your car hesitates to start, you should have the crankshaft position sensor inspected.
Do It Yourself Cost
If you decide to replace the crankshaft position sensor, you can do the job for around $80. We will show you how to do this by buying the sensor online and the necessary tools to complete this repair.
Frequently Asked Questions
How much does a Crankshaft Position Sensor Replacement Cost At an auto mechanic or dealership?
While the prices vary based on your location, the average cost of replacing the crankshaft position sensor at an auto mechanic or the Mercedes-Benz dealership varies between $250 and $400. The crankshaft position sensor cost between $100 and $150 at the dealership; that’s for the parts only.
What is the Best Scanner to Use for Diagnosing Mercedes-Benz Check Engine Light?
If you’re experiencing problems with your Mercedes-Benz, a YOUCANIC full system diagnostic scanner can help you troubleshoot the issues. This advanced diagnostic tool can read and interpret the fault codes stored in your car’s computer system, providing detailed information about any problems with the engine, transmission, brakes, or other critical systems.
The YOUCANIC scanner can also perform diagnostic tests on various systems, including the ABS, airbag, and steering systems, to help pinpoint the root cause of any issues. With this information, you can make more informed decisions about repairs and maintenance, saving time and money on costly repairs.
Where is the Crankshaft Position Sensor Location?
The CPS sensor is located near the firewall on the back of the engine.
Mercedes Crankshaft Position sensor replacement cost?
DIY costs around $50; if you have to take it to a shop, you will spend between $300-$400.
How long does it take to replace the crankshaft position sensor?
It will take you one to two hours to replace the sensor for the first time.
How difficult is replacing the crankshaft position sensor?
The sensor is held in place with one bolt. It is easy to replace the sensor; the hardest part is accessing it, as there typically isn’t enough room for your hands. In some models, it is easier than in others; it depends on how close the engine is to the firewall.
Where can I buy a crankshaft position sensor?
You can find a crankshaft position sensor for your Mercedes-Benz on Amazon. Even the OEM brand can be purchased online. See here:Crankshaft Position Sensor for Mercedes-Benz
VIDEO How to replace crankshaft position sensor on a Mercedes-Benz engine.
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Applicable Part Numbers and Models
Crankshaft Position Sensor CPS Part Numbers
Manufacturer Part Number: 003 153 27 28; 003 153 2828; A0031532728
Interchange Part Number: 0031532728; 0031532828; A0031532828
Other Part Number: 026 121 01 70; 0261210170
Replacement P/N: 003 153 27 28 / 003 153 2828 / A0031532728;
Replacement P/N: 0031532728 / 0031532828 / A0031532828 / 026 121 01 70 / 0261210170 / PC497;
Applicable Mercedes-Benz Models
– Mercedes-Benz C230 2002 2003 2004
– Mercedes-Benz C240 2001 2002 2003 2004
– Mercedes-Benz C32 AMG 2002 2003 2004
– Mercedes-Benz C320 2001 2002 2003 2004
– Mercedes-Benz C55 AMG 2005 2006
– Mercedes-Benz CL500 2001 2003 2004 2005 2006
– Mercedes-Benz CL55 AMG 2001 2002 2003 2004 2005 2006
– Mercedes-Benz CL600 2001 2002 2003 2004 2005 2006 2007 2008
– Mercedes-Benz CL65 AMG 2005 2006 2008
– Mercedes-Benz CLK320 2002 2003 2004
– Mercedes-Benz CLK430 2001 2002
– Mercedes-Benz CLK500 2003 2004 2005 2006
– Mercedes-Benz CLK55 AMG 2001 2002 2003 2004 2005 2006
– Mercedes-Benz E320 2001 2002 2003 2004 2005 2006
– Mercedes-Benz E430 2001 2002
– Mercedes-Benz E500 2003 2004 2005 2006
– Mercedes-Benz E55 AMG 2001 2002 2003 2004 2005 2006
– Mercedes-Benz G500 2002 2003 2004 2005 2006 2007 2008
– Mercedes-Benz G55 AMG 2003 2004 2005 2006 2007 2008
– Mercedes-Benz ML320 2001
– Mercedes-Benz ML350 2003 2004
– Mercedes-Benz ML430 2001
– Mercedes-Benz ML500 2003 2004 2005 2006 2007
– Mercedes-Benz ML55 AMG 2001
– Mercedes-Benz R320 2007 2008
– Mercedes-Benz R500 2007
– Mercedes-Benz S430 / S500 / S55 AMG 2001 2002 2005 2006
– Mercedes-Benz S600 2001 2002 2007 2008
– Mercedes-Benz S65 AMG 2007 2008
– Mercedes-Benz SL500 2001 2002 2003 2004
– Mercedes-Benz SL55 AMG 2003 2004 2005 2006 2008
– Mercedes-Benz SL600 2001 2002 2005 2006 2007
– Mercedes-Benz SL65 AMG 2005 2006 2007 2008
– Mercedes-Benz SLK230 2001 2002 2003 2004
– Mercedes-Benz SLK32 AMG 2002 2003 2004
– Mercedes-Benz SLK320 2001 2002 2003 2004
– Mercedes-Benz SLK320 2001 2002 2003 2004
– Mercedes-Benz SLK350 2005 2006
– Mercedes-Benz SLK55 AMG 2005 2006 2007 2008
– Mercedes-Benz SLR McLaren 2005 2006 2007 2008