The crankshaft position sensor is a sensor that tells the computer what position the engine is in. Then the computer knows where to fire the fuel injectors and when to fire the ignition spark plugs. So when they go bad, the car will often run very poorly. Is it safe to drive with a bad crankshaft position sensor?
”It is not safe to drive with a bad crankshaft position sensor because if the crankshaft position sensor is faulty, it can no longer supply the engine control unit with correct information about the position of the crankshaft. Not knowing the correct position, the ECU will not know when to fire the fuel injections and the ignition spark plugs and your vehicle won’t start, or can stall at any speed.”
How Does a Crankshaft Position Sensor Works
The crankshaft position sensor detects the crankshaft position and sends a signal to the ECU. The ECU or the engine control unit calculates the injection timing, ignition timing, and engine RPM according to the crankshaft position sensor signals. There are three types of crankshaft position sensors:
1. Optical Crankshaft Position Sensor
On most vehicles, the optical type is located at the distributor. It consists of LED, photo diode, and rotation slit. It monitors the crankshaft position depending on the slit location. To check the condition of the optical CPS you need to check the voltage between the sensor power terminal and ground terminal with your ignition turned on. Check if there’s zero or five voltage from the sensor signal wires.
2. Inductive Crankshaft Position Sensor
The inductive crankshaft position sensor consists of a permanent magnet and winding coil. The magnet flux field at the sensor responds as the teeth on the sensing teeth. The sensor generates AC voltage by rotation of the sensing teeth. The inductive sensor is normally a two-wire device. However, some sensors have three wires, the third being a coaxial shield wire to keep out any interference that may interrupt and corrupt the signal.
3. Hall IC Crankshaft Position Sensor
The Hall IC crankshaft sensor consists of a Hall element with a semiconductor. When magnet flux to the Hall element changes, the hall element is activated. It monitors the crankshaft rotation using a Hall-effect. The terminal of this sensor consists of 12-volts sensor power, 5-volts signal, and ground. Voltages at each terminal should be 12-volts, 5-volts, and 0-volt.
Most Common Signs of a Failing Crankshaft Position Sensor
When a crankshaft position sensor is bad or failing, it will give a series of signs that you can identify and diagnose your vehicle. To be absolutely sure about your diagnostics, you will need a scanning tool. (check prices on amazon.com). Here are the 5 most common signs of a failing crankshaft position sensor:
1. Vehicle cannot start
The crankshaft position sensor is part of the timing system. It monitors the speed of the crankshaft and its position. When the piston reaches to top dead center, the crankshaft position sensor sends information to the ECU, and the ECU coordinates with the ignition and fuel injection system.
When the crankshaft position sensor fails, simply due to normal wear and tear, obstructions, or interference it cannot perform its duties. Meaning, a faulty crankshaft position sensor can no longer send accurate information about the position of the piston and the computer will not spray fuel into the engine.
2. Vehicle stalls while driving
When the crankshaft position sensor is failing, it can cause intermittent stalling. The vehicle may stall at all speeds. The ECU will not receive any reliable signal from the crankshaft position sensor, therefore, interfering with the timing system. At this point, the engine may shut off at any time due to lost timing signal. Simply, the ECU will no longer spray fuel into the engine and your engine will shut off.
3. No fuel injection pulse
No fuel injection pulse is a sign of a failed crankshaft signal. The crankshaft sensor sends a signal to the ECU and the ECU determines when the fuel injector should spray fuel into the engine and how much.
It’s best if you use a scanning tool and run diagnostics on your vehicle. The scan tool will tell you exactly what is wrong with your vehicle.
4. No RPM movement while cranking
If the RPM needle on your dashboard is not moving while you are cranking your vehicle, this means there is no crankshaft signal. This symptom will not apply to all vehicles, but you can combine it with some of the previous symptoms and determine if your crankshaft position sensor is faulty.
5. Interference from
A broken timing chain, broken timing belt, broken harmonic balancer, and open wires can cause premature wear and failure to the crankshaft position sensor. A broken timing belt will damage the crankshaft position sensor and the interference engine.
Make sure the crankshaft position sensor is not wet from engine oil that could be leaking from the front seal or crankshaft seal. Also, check for coolant leaks from the water pump.
How To Replace a Bad Crankshaft Position Sensor
If your check engine light is on and your car is running poorly, there is a good chance that you have a bad crankshaft position sensor. What the crankshaft position sensor does is tells the ECU the position of the crankshaft. That way the ECU will know when to spray fuel and activate the spark plugs in the combustion chamber.
Here is how to replace a bad crankshaft position sensor:
1. Run diagnostics with a scan tool
Hook up a scan tool and run diagnostics on your vehicle just to make sure that you have a bad crankshaft position sensor. The error code for the faulty crankshaft position sensor is P0335. If you don’t have a scan tool, you can get one on amazon.com
2. Locate the crankshaft position sensor
So now the question comes, where is the crankshaft position sensor located? Most modern cars have the crankshaft position sensor between the engine and the transmission because they measure the flywheel spinning around.
3. Remove the crankshaft position sensor
You will need a little-bitty 10-millimeter socket wrench. There’s not much working room, so you might need an extension.
4. Install the new crankshaft position sensor
Once you have the old crankshaft position sensor, you can go ahead and install the new one. Just pop it back in the hole and then bolt it back in. You can order a new crankshaft position sensor on amazon.com.
5. Erase the error code with a scan tool
You have to reset the vehicle computer by erasing the old P0335 error code. Then go ahead and drive your vehicle. The check engine light should turn off at this point. After driving for a couple of miles, you can run diagnostics again just to double-check and make sure everything is alright.