Getting to KNOW MORE on Crankshaft Position Sensor

Learning more about Crankshaft Position Sensor

A crank sensor is an electronic device that monitors the position or rotation of the crankshaft in a gasoline or diesel engine. Engine management systems use this data to control fuel injection, ignition timing, and other engine parameters. Before electronic crank sensors, the distributor on petrol engines had to be manually adjusted to a timing mark.

How Crankshaft Position Sensor Work

In case you didn’t know, the crankshaft position sensor is an electronic device that is critical to a car’s operation. It is found in the vehicle’s engine. It measures the rate at which the crankshaft rotates. This sensor then sends the data to the ECU, which determines the best fuel injection and ignition timing. The effectiveness of the gathered data is determined by the location of the crankshaft. As a result, the sensor is either next to the camshaft or on the crankshaft itself.

If we try to put it another way, the crankshaft position sensor monitors the location of the camshaft within the engine. It uses the information gathered in this way to optimize the timing of fuel injection in the engine. If this sensor fails, the computer will be unable to fine-tune the fuel injection, causing the engine’s performance to suffer.

6 Symptoms of a Bad Crankshaft Position Sensor

1.) Vibrations in the engine

Is your engine causing you any discomfort? When the crankshaft position sensor fails, the engine control unit is unable to properly manage the crankshaft. Your engine will vibrate quite a bit as a result of this. As you hold the steering wheel in your hands, you may notice these vibrations sinking into it.

2.) Check Engine Light

The crankshaft position sensor is constantly communicated with by the engine control unit. If there is ever a problem with the sensor, the computer will receive incorrect information about the crankshaft’s speed and position.
This will cause engine malfunctions, resulting in the Check Engine warning light on the dashboard turning on. In fact, one of the first signs of a bad crankshaft position sensor should be this. P0335 is a common error code that may appear.

3.)  Engine Performance Issues

Your engine control unit will not know the correct position of the crankshaft or cylinders if the crankshaft position sensor is damaged. This will cause the control unit’s ability to maintain the engine’s operation and performance to be delayed.
During this time, there will be moments of hesitation every time you press harder on the gas pedal. It may or may not respond at all. On a road where you must go faster without hesitation, this can be extremely dangerous.

4.)  Car Isn’t Starting

When the crankshaft position sensor fails, the engine control unit will be notified. It receives a special malfunction code from the sensor, indicating that there is a problem with its operation.
When you try to start your vehicle while this problem is present, the engine will be more difficult to start. You may not be able to start your engine at all if the problem persists.

5.)  Stalling Engine

One day, you may be driving along when your engine suddenly stops running. When you have a bad crankshaft position sensor, this is known as engine stalling, and it can happen quite frequently.
If this sensor is not replaced soon, your engine will eventually stop working. You’ll have no choice but to have your car towed to a mechanic to have the sensor replaced.

6.) Misfiring Cylinders

If the crankshaft position sensor fails, the engine control unit will not be able to accurately transmit data about the piston position. A misfire in one or more of the chamber cylinders is common as a result of this.
A bad spark plug can also cause this, but if you’re experiencic

Crankshaft Position Sensor Location

The crankshaft position sensor’s location varies from vehicle to vehicle. Because it must be close to the crankshaft, it is usually found on the engine’s front underside. The timing cover is usually where you’ll find it.

location of crankshaft position sensor

Crankshaft Position Sensor Circuit

circuit of crankshaft position sensor

A Variable Reluctance Sensor (also known as a VR sensor) is a transducer that measures magnetic reluctance changes. The sensor detects changes in the presence or proximity of ferrous objects when combined with basic electronic circuitry.
A VR sensor can also measure linear velocity, angular velocity, position, and torque with the addition of more complex circuitry, software, and specific mechanical hardware.
The angular position of the crankshaft is provided to the Engine control unit by a crankshaft position sensor (in an automobile engine). Engine speed can then be calculated by the engine control unit (angular velocity).

Hall Effect Crankshaft Sensor : Magnetic field strength can be measured using a Hall-sensor. The magnetic field is disrupted when a metal object passes through the sensor. By pulling a voltage from the ECU to ground depending on the magnetic field strength, the sensor electronics convert the disruption of the magnetic field to a digital signal.

Crankshaft Position Sensor Relearn

If the diagnostic issue code P1336 is present, a crankshaft variation relearn is required. The computer has been reprogrammed or replaced. The position sensor for the crankshaft has been replaced. This enables the computer to detect an engine misfire across the whole RPM range of the engine.
Relearn a crank sensor without a scanner?
1. Turn off all of the accessories.
2. Drive the vehicle at part throttle to 55 mph.
3. Continue to cruise at 55 miles per hour for another 5-6 minutes.
4. Decelerate to 45 mph without touching the brakes, and keep it there for one minute.
5. Perform four 25-second deceleration cycles without applying the brakes, when no specified speed is required.

Testing of Crankshaft Sensor

 How To Tell If You Have an Inductive or Hall Effect CKP Sensor

Basically, most vehicles on the road today use one of two types of CKP sensors.

Inductive (magnetic) CKP sensor:

  • May have one or two wires
  • Mounts in front of a rotor or reluctor wheel
  • Produces its own AC voltage signal

Hall-effect CKP sensor:

  • May have three or four wires
  • Mounts in front of a rotor or reluctor wheel
  • Generates a digital (square wave) signal
  • Requires an outside power source and a ground to produce the signal

Testing an Inductive Type Crankshaft Position  Sensor

The following steps give you an example on how to test an inductive type CKP sensor.

Keep in mind that some manufacturers provide a protective shield along the sensor’s wiring, under the insulation. This prevents electrical interference. And there could be a third wire on the harness connector.

However, make sure to consult your vehicle repair manual for the electrical value specifications and, possibly, a recommended way to test the CKP sensor in your particular model, if necessary.

  1. Unplug the CKP sensor electrical connector.
  2. Set your digital multimeter to DC voltage scale using a low range.
  3. Turn the ignition key to the On position, but don’t start the engine.
  4. Touch the DMM black lead to ground. This can be a clean surface on the engine, a metal bracket or the battery negative (-) post.
  5. Touch the DMM red lead to each of the sensor wires on the harness connector you just unplugged. One of the wires should produce around 1.5 volts; otherwise, the sensor is not receiving a reference voltage, and needs to be fixed.
  6. To prevent the engine from starting:
    • Disable the fuel system by removing the fuel pump fuse or relay.
    • Or disconnect the ignition cable between the ignition coil and distributor.

    If necessary, consult your vehicle repair manual. This will prevent the engine from starting.

  7. Set your digital voltmeter to a low range on the AC voltage scale.
  8. Connect your meter leads to the sensor pins. Make sure to keep your meter lead wires away from engine moving parts during this test.
  9. Have an assistant crank the engine for a few seconds while you watch the meter’s readout.
  10. The sensor should produce a voltage pulsing signal. If you don’t see any voltage pulses, replace the sensor. If your multimeter can measure frequency (Hz), you can use this setting in the same way you check for an AC signal. Compare your results to the manufacturer specifications. Consult your vehicle repair manual.

You can check your inductive Crankshaft Position sensor’s resistance:

  1. Set your DMM to the Ohms scale.
  2. Unplug your CKP electrical connector.
  3. Connect one DMM lead to one of the sensor pins and the other DMM lead to the other sensor pin. It doesn’t matter which.
  4. Turn on your DMM.
    • The readout should indicate a resistance value, usually between 200 and 2000 ohms, depending on your particular vehicle model.
    • Compare your results to the manufacturer specifications. You may find the specification in your vehicle repair manual. If out of specification, replace the sensor.
    • If the readout is infinite resistance, the sensor has an open in the circuit;
    • If the readout is zero ohms, the sensor has a short circuit.

Testing a Hall Effect Type Crankshaft Position Sensor

Testing a Hall effect type sensor is best using an oscilloscope. But not many DIYers own one. Still, you can use a DMM to test this type of CKP sensor in your vehicle. And, unless stated in your vehicle repair manual, do not check the resistance of your Hall effect CKP sensor. The induced voltage may damage internal components.

Although you won’t see the high and low voltage graphic and frequency you see on an oscilloscope readout, you’ll get the average voltage coming from the sensor, which will give you an idea of its operation.

  1. Remove the fuel pump fuse or relay to prevent the engine from starting during this test.
    • If your engine uses a distributor, you can unplug the center ignition cable and ground it to the engine using a jumper wire.
    • If necessary, consult your vehicle repair manual.
  2. Unplug the CKP sensor electrical connector.
  3. Set your DMM to DC volts and to a range of 20 Volts.
  4. Touch the DMM black lead to the black wire on the harness connector.
  5. Touch the DMM red lead to the red (power) wire on the harness connector.
    • You may need to check the wiring diagram for your particular model, if the CKP sensor uses wires of different color to identify the ground, power and signal wires.
  6. Turn the ignition key to the On position.
  7. Your meter should read between 5 and 13 volts. Consult your vehicle repair manual for the reference voltage value for your particular model. If your reference voltage is lower than expected or zero, check the wire and connector for damage, or a loose terminal. If necessary, check your car’s computer.
  8. Turn the ignition Off and plug back in the CKP sensor to the harness connector.
  9. Set your DMM to a low DC voltage setting so that you can read millivolts.
  10. Touch the DMM black lead to battery negative.
  11. Then, using the meter red lead, back probe the black, ground wire at the harness connector or CKP sensor.
  12. Ask an assistant to crank the engine for a few seconds. Your DMM should register about 200mv to 300mv.
  13. Now, touch your DMM red lead to the green (signal) wire on the harness connector or CKP sensor.
  14. Crank the engine for a few seconds. You meter should register around 300mv. This is an average voltage value of the signal the CKP sensor produces.

If necessary, compare your results to the specs in your vehicle repair manual.

If your multimeter can read Duty Cycle signals, you may be able to detect a CKP signal as well, depending on your particular system. You can do this by backprobing the signal wire on the sensor and connecting the DMM black lead to ground.

  • Set your DMM to Duty Cycle and ask an assistant to crank the engine.
  • If the CKP doesn’t produce a duty cycle signal, the sensor may be bad.

11 Crankshaft Position Sensors OBD DTC Codes

P0389 Crankshaft Position Sensor B Circuit Intermittent

Because P0389 refers to a circuit fault, we may narrow our attention to electrical issues, but we cannot rule out the possibility of a sensor or reluctor ring malfunction. In this case, however, we may apply the same troubleshooting procedures as we did for the CMP sensor and signal to identify why DTC P0389 is recorded in the ECU memory because the CKP sensor and signal are extremely similar in nature.

Verify that all connectors are correctly connected by performing a visual inspection. Damage to the wire harness should be looked for.

When inspecting the sensor, look for resistance; an open-circuit or short-circuit indicates a definite defect; nevertheless, verify the service manual for the correct resistance range. If you have a DVOM (digital volt-ohm meter), set it to AC mV and crank the engine, you should be able to check for signal.

Wiring Harness Inspection: Inspect the wiring harness between the ECU and the CKP sensor for any open circuits or short circuits.

P0388 Crankshaft Position Sensor B Circuit High Input

What the code P0388 means and what it means to you. If the crankshaft position sensor sends a voltage signal that is higher than the maximum allowed, the car’s computer will record the code P0388. The signal will be around 10 percent stronger than the specifications set by the OEM. In addition, the Check Engine light will illuminate.

P0387 Crankshaft Position Sensor B Circuit Low Input

According to normal operation, the crankshaft position sensor records and transmits to the PCM the speed at which the crankshaft is spinning and its present location to the engine management system. Using this information, the PCM may control various tasks like as ignition timing and fuel flow. P0387 codes are saved when the circuit input for this sensor is too low, irregular, or otherwise outside normal bounds by more than 10%. This is because an improper voltage input can have a negative impact on the engine’s operation.

P0386 Crankshaft Position Sensor B Circuit Range/Performance

The presence of the trouble code P0386 indicates that the vehicle’s computer has detected high voltage from the crankshaft position sensor, which has exceeded the manufacturer’s specifications. The cause of the excessive voltage is unknown. When the P0386 error code is shown, it means that the Crankshaft Position Sensor B Circuit Range Performance has failed.

P0385 Crankshaft Position Sensor B Circuit Malfunction

Possible reasons of the P0385 code Crankshaft position sensor failure The harness for the crankshaft position sensor is open or shorted. Circuit for the crankshaft position sensor has a bad electrical connection. It’s possible that the signal plate is damaged. It’s possible that the starter motor is broken. Circuit for starting the system The battery is either dead or weak.

P0339 Crankshaft Position Sensor A Circuit Intermittent

What Does the P0339 Code Indicate? P0339 is a diagnostic issue code that stands for “Crankshaft Position Sensor “A” Circuit Intermittent.” It means that the powertrain control module (PCM) has recognized or failed to detect an abnormal signal from the crankshaft position sensor.

P0338 Crankshaft Position Sensor A Circuit High Input

What does the P0338 code mean? The powertrain control module has discovered that the crankshaft position sensor, or CPS, is malfunctioning.

P0337 Crankshaft Position Sensor A Circuit Low Input

What Does P0337 Stand For?
The engine requires three things to function: air, fuel, and a spark plug. To function properly, the engine control module (ECM) precisely measures how much fuel to inject for the measured mass of air at any particular time, and then delivers a spark to ignite a power stroke hundreds of times per second. Of course, all of this requires exact timing, which the ECM achieves through the use of camshaft and crankshaft position sensors (CMP and CKP).

The crankshaft position signal performs two critical roles. For starters, it serves as a speed sensor, allowing the ECM to determine engine speed in revolutions per minute (rpm). Second, CKP acts as a position sensor, allowing the ECU to calculate the location of cylinder #1 at top-dead-center (TDC). The ECU calculates injector pulse width (IPW), ignition timing, and variable valve timing (VVT), among other things, using rpm and TDC readings, and it can even detect cylinder misfires.

If the ECU is unable to detect enough voltage from the CKP sensor, DTC P0337 Crankshaft Position Sensor “A” Circuit Low Input is set.

P0336 Crankshaft Position Sensor A Circuit Range/Performance

The powertrain control module (PCM) has detected an issue with the crankshaft position sensor (CPS) or circuit if the code P0336 is stored. Sensor A represents the principal crankshaft position sensor in a system that may use numerous crankshaft position sensors for diverse functions.

The PCM monitors the engine’s position and revolutions per minute (RPM) using input signals from the CPS and the camshaft sensor/s, manages ignition timing variations, and calculates fuel supply strategy. The number of camshaft sensors utilized in conjunction with a single CPS is determined by engine layout.

Each camshaft sensor has a circuit (or circuits) dedicated to supplying unique input signals to the PCM. Because the crankshaft rotates at twice the speed of the camshaft/s, the PCM must be able to discriminate between engine intake and exhaust stokes. In order to prevent engine damage, the crankshaft position and speed are compared to the speed and position of the camshaft/s.

The most typical CPS design employs an electromagnetic hall-effect sensor placed very close to the crankshaft (generally only a few thousandths of an inch) to generate a circuit complete engine ground. In most situations, this engine ground is provided by a reluctor ring (with carefully machined teeth) attached to the crankshaft or crankshaft pulley. In other circumstances, the engine ground is provided by cogs meticulously fitted into the crankshaft itself.

The CPS is designed in such a way that these teeth/cogs pass quite close to its magnetic end. The elevated regions pass by the sensor as the crankshaft turns, completing the electromagnetic circuit. The circuit is briefly broken when the indentations (between the teeth) travel through the CPS. Because the camshaft rotates at such a high rate, the process of continually completing and stopping the circuit takes milliseconds. The sequence of completing and interrupting the CPS circuit results in a waveform pattern. The PCM recognizes this pattern as crankshaft position. The CPS and all of the camshaft position sensors work in the same way.

The PCM constantly compares input data from the crankshaft and camshafts while the engine is running. A P0336 code will be stored and a malfunction indication lamp may illuminate if the crankshaft position is not within a certain degree of variation from the camshaft/s under a specific set of circumstances for a specific amount of time.
When this code is set, the engine usually does not start. If the engine does start, it will almost certainly run poorly.

P0335 Crankshaft Position Sensor A Circuit Malfunction

It is stated as Crankshaft Position Sensor “A” Circuit Malfunction in the description of Error Code P0335. In this case, the ECM (Electronic Control Module) of the car has not yet noticed the crankshaft position sensor during the first second of the engine’s cranking cycle.

P1336 code, crankshaft position sensor variation not learned

When the Crankshaft Position System Variation is not within an acceptable range or cannot be learned, the DTC P1336 is set. When the diagnostic procedure is attempted and fails, the PCM illuminates the malfunction indicator lamp (MIL). The PCM keeps track of the operational conditions that existed at the time of the diagnostic failure.



Thank you very much! This tutorial is humble made and research by Erwin Salarda