Crankshaft position sensor: Difference between revisions

From W220 S-Class Encyclopedia
Jump to navigation Jump to search
m (→‎Description: changed part 15 to part 5)
m (Clarified some detail and added resistance specification.)
Line 1: Line 1:
==Description==
==Description - CPS==


{|
{|
Line 8: Line 8:


The crankshaft position sensor (CPS) is located on car's left side, towards the rear of engine. Back of engine, near the firewall.
The crankshaft position sensor (CPS) is located on car's left side, towards the rear of engine. Back of engine, near the firewall.
It monitors the engine crankshaft position and speed and is one of the most important input sensors that is used by the Engine Control Unit (ECU).  
It monitors the engine crankshaft position and speed and is one of the most important input sensors that is used by the Engine Control Unit (ECU). It sends information about the position of the crankshaft and speed of the engine RPMs to the ECU which is then used to fire the spark plugs and to adjust the fuel mixture.
If the crankshaft position sensor fails, it will not send information about the position of the crankshaft 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.
==Issues - CPS==
This can cause your car to stall or hesitate to start.  
M-B CPS often fail completely or become intermittent. If the crankshaft position sensor fails, it will not send information about the position of the crankshaft and speed of the engine RPMs to the ECU. As a result, the ECU doesn't know when to fire the spark plugs and how to adjust the fuel mixture. This can cause your car to stall or hesitate to start.  


Problems with the Crankshaft Position Sensor on Mercedes-Benz cars are fairly common.
If you have been experiencing stalling or no start conditions, a failed crankshaft position sensor is often the problem.
If you have been experiencing stalling or no start conditions, a failed crankshaft position sensor is often the problem.


Line 23: Line 22:
* Impact on transmission shifting. In some cases, it can cause the transmission to go into limp mode.
* Impact on transmission shifting. In some cases, it can cause the transmission to go into limp mode.


Hint: If you are stuck on a parking lot and the car will not start, let the car cool down at least 30 minutes and then try again.
'''Hint:''' If you are stuck on a parking lot and the car will not start, let the car cool down at least 30 minutes and then try again.
What happens is when the car gets hot, the sensor's resistance goes open circuit, thus the car dies.
Now since the sensor is still hot, the sensor is still open circuit, but once it cools off, the resistance comes back into spec, thus the car starts.


Often when the car gets hot, the sensor gets hot and the sensor's resistance goes open circuit, thus the car dies. Once the engine and sensor cool down, and if you are lucky, the resistance may come back into spec, thus the car starts again.
==Fault Codes - CPS==
If your check engine light is on, then your ECU has recorded some sort of trouble code. You can check these codes with a diagnostic scan tool.
If your check engine light is on, then your ECU has recorded some sort of trouble code. You can check these codes with a diagnostic scan tool.
Codes between P0335 and P0339 correspond to crankshaft sensor problems.
Codes between P0335 and P0339 correspond to crankshaft sensor problems.
This is probably the most straightforward and the most certain way to test for and identify a crankshaft sensor problem.
This is probably the most straightforward and the most certain way to test for and identify a crankshaft sensor problem.
'''Unfortunately, the crankshaft sensor is usually pretty far gone by the time that the check engine light is on.'''
'''Unfortunately, the crankshaft sensor is usually pretty far gone by the time that the check engine light is on.'''
You might already be experiencing crankshaft sensor problems before the ECU has noted any sign of trouble.
You might already be experiencing crankshaft sensor problems before the ECU has noted any sign of trouble.


Line 53: Line 57:
|}
|}


==Parts==
==Part Numbers - CPS==
W220 uses magnetic impulse triggering sensor with two wires.
W220 uses magnetic impulse triggering sensor with two wires.
* CPS OE A0031532728 (Replaced by A0031532828)
* CPS OE A0031532728 (Replaced by A0031532828)
Line 70: Line 74:
|}
|}


==DIY Replacement==
==DIY Tests - CPS==
The CPS can be tested by measuring its resistance and checking whether it generates voltage.
'''Resistance Testing'''
* Remove the sensor. (See section 'DIY Replacement - CPS' below.)
* Measure the resistance by attaching a multi-meter to each male pin in the sensor connector.
[[File:CPS Internal Resistance Measurement.JPG|500px|center]]
* Check the result against the manufacturer's specification. M-B WIS states for a W220 that the internal resistance of the sensor unit should be between 0.6K Ohms and 1.3K Ohms.
* Resistance of zero means that there is a short circuit.
* Infinite resistance means there is an open circuit.
* Repeat the resistance measurement while heating the sensor with a hair drier or heat gun. A CPS will often give a reading within spec when at ambient temperature but produce an open circuit after being heated slightly. The OEM (Bosch) CPS in the above figure produced a resistance of 1.097K Ohms at 25C and went open circuit when heated slightly.
*If your reading is not close to the recommended resistance, then you should replace the sensor.
 
'''Voltage Testing'''
* Another way to test the crankshaft sensor with a multi-meter is by checking the output voltage with the engine cranking. You will need an assistant to do this. Be very careful around moving parts as you do this.
* Probe the wiring connectors and measure the output voltage in AC millivolts. Typically, this reading is around 200 millivolts, but this can vary from vehicle to vehicle. Check the manufacturer's specifications.
* If there is no output voltage, then, obviously, your sensor is not working.
 
{|
|{{#ev:youtube|https://www.youtube.com/watch?v=sVMu8Nac9q4|320|left|Testing CPS resistance.|frame}}
|{{#ev:youtube|https://www.youtube.com/watch?v=RvuzZJqQDf4#t=185|320|left|Testing CPS voltage generation.|frame}}
|}
 
==DIY Replacement - CPS==
{|
{|
|[[File:E8_torx_socket.jpg|thumb|none|Torx screw in E8 torx female socket.]]
|[[File:E8_torx_socket.jpg|thumb|none|Torx screw in E8 torx female socket.]]
Line 94: Line 120:


Note: If a heat shield is installed, there may be too small space for hand to fit.
Note: If a heat shield is installed, there may be too small space for hand to fit.
The way around it to not actually remove the connector,
The way around it to not actually remove the connector, but just blindly remove the E8 torx bolt and use the connector and attached cable to remove the CPS.
but just blindly remove the E8 torx bolt and use the connector and line to fish the CPS out.


{|
{|
Line 102: Line 127:
|}
|}


==DIY Tests==
== Resources - CPS==
 
CPS can be tested by measuring its resistance and checking whether it generates voltage.
 
* You can remove the sensor, and then test the resistance. Attach one end of the multimeter to each wiring lead of the sensor. Resistance of zero means that the there is a short circuit. Infinite resistance means there is an open circuit. Either one of those readings indicates that the sensor is not working. For any other reading, check it against the manufacturer's specifications. If your reading is not close to the recommended resistance, then you should replace the sensor.
* Another way to test the crankshaft sensor with a multimeter is by checking the output voltage with the engine cranking. You will need an assistant to do this. Be very careful around moving parts as you do this. Probe the wiring connectors and measure the output voltage in AC millivolts. Typically, this reading is around 200 millivolts, but this can vary from vehicle to vehicle. Check the manufacturer's specifications. If there is no output voltage, then, obviously, your sensor is not working.
 
{|
|{{#ev:youtube|https://www.youtube.com/watch?v=sVMu8Nac9q4|320|left|Testing CPS resistance.|frame}}
|{{#ev:youtube|https://www.youtube.com/watch?v=RvuzZJqQDf4#t=185|320|left|Testing CPS voltage generation.|frame}}
|}
 
== Resources ==
* http://www.doityourself.com/stry/warning-signs-of-a-bad-crankshaft-position-sensor
* http://www.doityourself.com/stry/warning-signs-of-a-bad-crankshaft-position-sensor
* http://www.mercedesmedic.com/crank-shaft-position-sensor/
* http://www.mercedesmedic.com/crank-shaft-position-sensor/

Revision as of 07:59, 2 January 2017

Description - CPS

Crankshaft position sensor (CPS).
CPS in engine (crosscut).
CPS in EPC schematic (part 5).

The crankshaft position sensor (CPS) is located on car's left side, towards the rear of engine. Back of engine, near the firewall. It monitors the engine crankshaft position and speed and is one of the most important input sensors that is used by the Engine Control Unit (ECU). It sends information about the position of the crankshaft and speed of the engine RPMs to the ECU which is then used to fire the spark plugs and to adjust the fuel mixture.

Issues - CPS

M-B CPS often fail completely or become intermittent. If the crankshaft position sensor fails, it will not send information about the position of the crankshaft and speed of the engine RPMs to the ECU. As a result, the ECU doesn't know when to fire the spark plugs and how to adjust the fuel mixture. This can cause your car to stall or hesitate to start.

If you have been experiencing stalling or no start conditions, a failed crankshaft position sensor is often the problem.

Symptoms of fault:

  • The engine may crank, but it will not start (starting problems are initially random, but more frequent when the engine is hot).
  • The engine cranks longer in order to get it to start.
  • Car runs for a short time, or until it gets warm and then it dies.
  • Poor acceleration, engine vibrations, poor throttle response, bad fuel economy.
  • Impact on transmission shifting. In some cases, it can cause the transmission to go into limp mode.

Hint: If you are stuck on a parking lot and the car will not start, let the car cool down at least 30 minutes and then try again.

Often when the car gets hot, the sensor gets hot and the sensor's resistance goes open circuit, thus the car dies. Once the engine and sensor cool down, and if you are lucky, the resistance may come back into spec, thus the car starts again.

Fault Codes - CPS

If your check engine light is on, then your ECU has recorded some sort of trouble code. You can check these codes with a diagnostic scan tool.

Codes between P0335 and P0339 correspond to crankshaft sensor problems.

This is probably the most straightforward and the most certain way to test for and identify a crankshaft sensor problem.

Unfortunately, the crankshaft sensor is usually pretty far gone by the time that the check engine light is on.

You might already be experiencing crankshaft sensor problems before the ECU has noted any sign of trouble.

Error Code Description
P0335 Crankshaft Position Sensor A Circuit Malfunction (L5)
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

Part Numbers - CPS

W220 uses magnetic impulse triggering sensor with two wires.

  • CPS OE A0031532728 (Replaced by A0031532828)
  • CPS OE A0031532828 (~125EUR)
  • CPS BOSCH part 0261210170 (~50EUR)
  • Screw N910142006001
  • Pin bushing housing A1685453028
Bosch part 0261210170.
Bosch part 0261210170.
Screw (N910142006001).
Pin bushing housing (A1685453028).

DIY Tests - CPS

The CPS can be tested by measuring its resistance and checking whether it generates voltage. Resistance Testing

  • Remove the sensor. (See section 'DIY Replacement - CPS' below.)
  • Measure the resistance by attaching a multi-meter to each male pin in the sensor connector.
  • Check the result against the manufacturer's specification. M-B WIS states for a W220 that the internal resistance of the sensor unit should be between 0.6K Ohms and 1.3K Ohms.
  • Resistance of zero means that there is a short circuit.
  • Infinite resistance means there is an open circuit.
  • Repeat the resistance measurement while heating the sensor with a hair drier or heat gun. A CPS will often give a reading within spec when at ambient temperature but produce an open circuit after being heated slightly. The OEM (Bosch) CPS in the above figure produced a resistance of 1.097K Ohms at 25C and went open circuit when heated slightly.
  • If your reading is not close to the recommended resistance, then you should replace the sensor.

Voltage Testing

  • Another way to test the crankshaft sensor with a multi-meter is by checking the output voltage with the engine cranking. You will need an assistant to do this. Be very careful around moving parts as you do this.
  • Probe the wiring connectors and measure the output voltage in AC millivolts. Typically, this reading is around 200 millivolts, but this can vary from vehicle to vehicle. Check the manufacturer's specifications.
  • If there is no output voltage, then, obviously, your sensor is not working.
Load video
YouTube
Testing CPS resistance.
Load video
YouTube
Testing CPS voltage generation.

DIY Replacement - CPS

Torx screw in E8 torx female socket.
CPS location.
CPS electrical plug.
CPS attached to engine.
CPS attached to engine.
Removing screw using ratchet.

Tools needed:

  • E8 torx 1/4 socket.
  • Ratchet with 6-inch 1/4 extension.

Steps:

  1. Remove engine cover.
  2. Unplug the electrical connector from the CPS sensor.
  3. Remove bolt using E8 torx socket.
  4. Install in opposite order.

Note: If a heat shield is installed, there may be too small space for hand to fit. The way around it to not actually remove the connector, but just blindly remove the E8 torx bolt and use the connector and attached cable to remove the CPS.

Load video
YouTube
CPS replacement on pre-facelift.
Load video
YouTube
CPS replacement (including heat shield removal).

Resources - CPS

Retrieved from "https://w220.wiki/index.php?title=Crankshaft_position_sensor&oldid=4826"