Knowing the symptoms of a failing camshaft position sensor will help a lot with your driving experience.
Why? Because the camshaft position sensor (CMP) monitors the rate in which the camshaft rotates. The camshaft is basically a rod/shaft that has protrusions which open and close certain valve in the engine.
A working camshaft sensor monitors the sequence of opening/closing the camshaft does and sends that information to the computer (engine control unit – ECU) of the vehicle.
With that information, the ECM can control the timing of the ignition and fuel injection. So, inherently, your vehicles CMP sensors are very important to the efficiency of your vehicles engine and ultimately, your driving experience.
So, what happens if the camshaft sensor goes bad? Well, instances like this could lead to very bad situations like you losing power in the middle of the highway.
That is why this article will look at some of the symptoms of a failing CMP sensor so that you can avoid those types of situations.
What is Camshaft Position Sensor?
The camshaft position sensor is an electronic device in an engine that monitors the camshaft’s rotation and position to deliver the information to the vehicle’s engine control module (ECM).
The ECM uses the data to determine when it can command spark and fuel for the best performance and efficiency of the engine. When the right air/fuel mixture ignites in the engine at the right time, engine power and fuel savings are increased, and tailpipe emissions are decreased.
In newer types of engines, the camshaft position sensor will decide which cylinder is in its power stroke in relation to the crankshaft position which allows for fuel and spark to be provided to start the engine when you push down on the accelerator.
The sensors are usually attached to the engine so that they pull power from the electrical connection. A camshaft position sensor is a very small but crucially significant magnetic device.
Camshaft Position Sensor Function
To help understand the operation of the camshaft position sensor, we can use an example.
In an internal combustion engine, the engine valves are opened by the camshaft, allowing air/hydrogen fuel to enter the combustion chamber at the command of the ECM.
All of the valves are then closed so that the piston can compress the air and fuel mixture in the combustion chamber. The ECM then commands spark for combustion when the piston reaches the top. The explosion then pushes that piston down the rest of the way to provide power to the engine.
The camshaft then opens the exhaust valves while the piston comes back up so the gases can exit to the exhaust manifold. All of this occurs while there is combustion happening in the engine in concert with the camshaft position sensor.
Camshaft Position Sensor Location
The precise location of the camshafts varies depending on the engine’s make, model, and construction, but usually will be somewhere by the camshaft. By design, the camshaft position sensor is typically found close to the front side or top of the engine.
This is either going to be on the top of the cylinder block, one of the two ends, or usually on the intake manifold where its located near the timing cover. At times, the camshaft sensor may be in the back of the timing cover.
Typically it is as simple as removing the cover for a given engine, and you will find it location the camshaft position sensor right on the back of the engine.
How does the camshaft position sensor work?
The camshaft position sensor uses the magnet in its sensor to detect rotation of the camshaft. The movement of the rotor will cause the magnetic field emanating from the magnet to vary according to the position of the detection tooth in relation to the camshaft position sensor.
This occurs as the detection tooth, connected to the timing rotor, moves to and fro in relation to the camshaft position sensor.
The value of the MRE (magnetic resistance element) will thus also vary while the engine’s ECU voltage is applied to the camshaft position sensor. At the same time, the change in MRE resistance value manifests itself as a change in the voltage.
Along the way, the waveforms of the MRE’s outputs are varied in amplification and take on a rectangular waveform which is modified by a circuit incorporated into the sensor. The MRE outputs or voltage is processed and sent to the engines ECU.
Types of Camshaft Position Sensor
There are three primary camshaft position sensor types:
- Magnetic type sensor
- Hall effect sensor
- A.C. output sensor
#1. Magnetic Type Sensor.
The magnetic type camshaft position sensor is recognizable by its two wires that generates its own voltage, an alternating current (AC) sine wave signal. It is located inside the distributor or on the camshaft.
As it is in close proximity to the camshaft, it has a permanent magnet device that is attached to it. Each time the magnet goes through the sensor, a magnetic field is generated which creates a pulse. The pulse is sent to the ECM for processing.
#2. Hall Effect Sensor.
This camshaft sensor has three wires – one for reference power, one for ground, and one for the signal voltage to be sent to the computer. This Hall Effect sensor also sits inside the distributor or on the camshaft.
It has a screen with a slot and a magnet mounted on the shaft. When the screen moves between the magnet and the sensor, the sensor turns on and off.
As long as the screen has a solid area in front of the sensor, the feedback voltage is interrupted as the magnetic field splits.
#3. A.C. Output Sensor.
These are specific varieties of camshaft position sensors that produce an AC voltage signal as an output. The ECM produces an extremely high frequency (150 to 2500 cycles) for the exciter coil, which is situated close to the rotating disc.
This disc is installed on the end of the camshaft and has a slotted timing disk. When the slot comes through the coil, the coil is excited by mutual induction, and a signal indicating the position of the first cylinder is sent to the ECM. This sensor is mostly seen in Vauxhall ecoTEC engines.
Symptoms of a bad camshaft position sensor
Your vehicle has a CMP sensor, and like all of its components, the sensor will eventually go bad. Some of the symptoms are as follows.
#1. Blinking check engine light.
One of the more common symptoms of a faulty CMP sensor is the illumination of the check engine light on your dashboard.
However, this symptom does not mean that the CMP is bad, as that light could go on for other issues. It is best to run a camshaft position sensor test with an OBD2 scan tool.
After you scan the car for trouble codes, only then can you begin determining what is wrong with the CMP sensor. If the OBD2 tool tells you the crankshaft position sensor is bad, or you do not get a trouble code, then you should have a qualified mechanic look to see what is wrong.
#2. Starting issues.
Typically, this is a degenerative symptom that arises because your car’s CMP sensors are in such poor condition.
As the CMP sensor continues to deteriorate, the signal decreases from the CMP sensor to the car’s engine. After a while, the signal is completely lost. You will then have trouble starting it; it also may only be hard starting from time to time.
#3. Stalling vehicle.
Your vehicle will stall and backfire or misfire following a faulty CMP. Here’s the reason why; The fuel injectors are no longer receiving signals to deliver fuel to the engine cylinders at the right time.
Once this happens, the engine loses power and starts stalling. At this point, the engine can go into limp mode. Limp mode is where the car locks into one gear and does not accelerate beyond a set speed.
#4. Fuel system issues.
The CMP sensor regulates the amount of fuel delivered to the engine cylinders. It sends signals to the car computer that measures the timing and length of time that fuel it delivered to the engine cylinders.
When a CMP fails, it can no longer do this, since the CMP is causing your car fuel injectors to provide no pulse. This causes issues with the fueling system, and other complexities.
#5. Acceleration issues.
A faulty CMP sensor can cause delays in fuel delivery. This means that the signals sent from the failing CMP sensor are wrong, or inconsistent.
This will affect the timing and amount of fuel injected, affecting how the throttle responds and causing poor acceleration.
#6. Transmission problems.
A malfunctioning CMP sensor can cause transmission problems in cars that have automatic transmission.
If you drive an automatic transmission and notice that the vehicle is stuck in one gear and not shifting, it is because of the CMP sensor failing or the vehicle entered limp mode.
#7. Decreased fuel mileage.
If a faulty CMP sensor sends incorrect readings, your engine may be injecting too much fuel, wasting fuel economy.
Bad gas mileage can also happen when a bad camshaft sensor sends incorrect signals that cause fuel injected into the engine improperly and allow a lot of unburned fuel to exit the exhaust.
CMP sensors send excessive fuel to the engine’s cylinders when they send improper signals that affect how long and when the fuel injector opens.
Exhaust shows up black when excessive fuel enters the exhaust because the exhaust cannot burn all of the fuel. The unburned fuel leaves your exhaust from your tailpipe, causing emission issues.
#8. Jerking car.
A faulty camshaft sensor can cause a car to jerk when the wrong amount of fuel is injected or the engine loses power while the vehicle is moving. The jerking motion is simply the car’s response to any of these situations.
Now that you know the symptoms that may happen from a bad camshaft sensor, is it safe to continue driving if you get positive symptoms?
As addressed before, we recommend that you fix the problem as soon as you see either of the symptoms addressed above. You’ll be saving yourself an engine from possible damage, which in return saves you from repairs that could be costly, and or potential accidents that could occur while driving a faulty vehicle.
Camshaft Position Sensor Replacement Cost
Replacing a camshaft position sensor costs $170 to $220. Parts prices and labor costs will be itemized. Taxes will be also be added to the combined costs.
Replacing the camshaft position sensor involves following these steps:
- The first step is to disconnect the negative battery cable.
- The second step is to locate the sensor. It will usually be on the top, front, or rear of the engine. There will also be a 2-3 wire connector attached to it as well.
- Now that you have found the sensor you will have to release the tab on the sensor to disconnect the wires from the sensor.
- Now you will remove the mounting bolt that attaches the sensor to the engine. The mounting bolt is usually a size 8mm or 10mm.
- Now that the mounting bolt has been removed carefully pull off the worn camshaft position sensor with some twisting.
- While installing a new camshaft position sensor you will have to apply some engine oil to the O-ring of the new sensor.
- Now install the sensor and install the mounting bolts to secure the sensor in place.
- Reconnect the wire connector to the sensor properly.
- The final step is to reinstall the negative terminal on the battery.
- After the completion of this task take the vehicle for a test drive to determine if the camshaft position sensor is functional or not.
FAQs.
Q: What does a bad camshaft sound like?
A bad camshaft can produce certain sounds to let you know that something is wrong.
Usually, a bad camshaft is associated with ticking, tapping, and popping sounds. There will also be an abundance of backfiring as the car engine’s cylinders misfire at varying speeds.
Q: What does the camshaft position sensor do?
The camshaft position sensor lets a car’s computer system, or powertrain control module (PCM), know where the crankshaft drive is at any given time. It also allows the PCM to ascertain the location of each of the engine’s cylinders.
This information allows the car’s computer to determine fuel injection and ignition timing and duration. This facilitates a smooth combustion process and proper engine performance.
Q: How long does it take to change the camshaft?
The time it takes to change a camshaft is determined by several reasons. These reasons include the make/model of the car, as well as where the camshaft is mounted.
Camshafts mounted in an easy-to-reach location are faster to change than camshafts to change on an engine with an awkward configuration.
That said, changing a camshaft takes less than 24 hours, and sometimes a lot less. It is best to have the camshaft changed but be sure to get someone knowledgeable enough to reset the camshaft position sensor after.
Q: How does a camshaft sensor differ from a crankshaft position sensor?
The camshaft sensor tracks the movement of the camshaft and sees which specific cylinder is firing at any point in time.
This camshaft movement and cylinder information is sent to the ECU so it can use the information to manage other aspects of the engine processing such as ignition timing and fuel injection.
The crankshaft position sensor monitors the crankshaft of the car which turns the crankshaft thereby turning the car engine, harvesting the force from the pistons of the combustion event.
It is responsible for getting the engine’s relative speed and diameter for the ignition timing.
Q: Where can a camshaft position sensor be located?
It depends on your car’s make and model, as most manufacturers have different locations for the camshaft position sensor.
A camshaft position sensor can be located generally anywhere – either next to the engine block, in the lifter valley, on the back of the engine cylinder head, or an area specifically set aside for a camshaft position sensor.
However, in most cases of cars, the sensor is located somewhere near the top of the engine.
The camshaft position sensor can be located under the intake manifold either from the front or back of the cylinder heads or somewhere around the timing cover. You may want to refer to your owner’s manual to get the appropriate area for the camshaft position sensor.
Q: How many camshaft sensors are there?
There are two camshaft sensors: Magnetic camshaft sensor and Hall-effect camshaft sensor. Both sensors send signals to the car’s computer.
While the Magnetic camshaft sensor produces its own signal for the car. Hall-effect camshaft sensors only works with an external power source to create a digital signal.
Magnetic camshaft sensor has two wires and Hall-effect camshaft sensor has three. Hall-effect camshaft sensors are usually what newer cars use.
Q: How much does it cost to replace camshaft position sensor?
The cost of replacing the camshaft position sensor will depend on the make and model of the car, if you do it yourself or pay a mechanic, and where you get it done; however there are several factors to consider during the process of replacing the camshaft position sensor.
If you do it yourself, it will cost $25-$100 depending on your car.
If a professional mechanic, does it, it will cost around $70-$100, depending on the make and model and where you are getting it done (dealerships and luxury cars typically cost more).
So ultimately, if you weigh all of the differences your final cost for a new camshaft position sensor will be between $25-$100. Your best bet, however, is to give these certified mechanics a call once you find out what is wrong with your car.
Mechanics or whoever replacing, they know what to look for and replace after the camshaft position sensor has been replaced.
Closing It Up
The camshaft position sensor operates similarly to the crankshaft position sensor.
In some cars, the engine control module might compensate for one or the other. However, always attending to the sensor signals to prevent damaging your engine is advisable.