The camshaft and crankshaft are two vital components of an engine. The engine highly depends on the data provided by both the crankshaft position sensor and the camshaft position sensor to ensure optimal performance. Therefore, a malfunction in either of these sensors can have a significant impact on your vehicle’s fuel economy and overall performance. This article mainly explains the bad camshaft position sensor symptoms, causes, and how to replace it.
What is a Camshaft Position Sensor?
A camshaft position sensor (CMP sensor) is a part of the engine that is used to measure the camshaft position and rotational speed. It sends this data to the powertrain control module (PCM), which utilizes it to regulate the fuel injection rate, the air-fuel ratio in the combustion chamber, and ignition timing.
The information of the CMP sensor helps the PCM to optimize the engine performance. When the air-fuel mixture burns at precisely the right time, engine power and fuel economy increase, and exhaust emissions decrease.
The cam sensor usually uses an optical sensor, a magnetic sensor, or a Hall effect sensor to monitor the position of the camshaft relative to a reference point. When the camshaft turns, the sensor produces a voltage signal that alters according to the position of the camshaft, permitting the PCM to determine the correct position of the camshaft.
Bad Camshaft Position Sensor Symptoms
As the camshaft position sensor goes bad, it produces one of the below-given symptoms:
- The engine won’t start
- Check engine light illumination
- Car jerking
- Ignition issues
- Poor engine performance
- Fuel system issues
- Engine misfire
- Engine stalling
- Poor acceleration
- Transmission issues
- Rough idling
- Failed emissions test
- Gas smell
- Poor fuel economy
1) Hard Starting
One of the most common signs of a faulty camshaft position sensor is that your vehicle engine will be hard to start, or the engine won’t start at all.
The camshaft sensor sends data about the camshaft performance to the powertrain control module (PCM). The PCM regulates the fuel injection ratio, ignition timing, and air-fuel ratio according to the data received by the camshaft sensor.
As the sensor goes bad, it may send wrong data to the PCM, leading to poor combustion of the air-fuel mixture.
Without the proper combustion of the air-fuel mixture, your engine may fail to start, indicating a potential issue with the camshaft sensor. In some latest vehicle models, if the cam position sensor isn’t working efficiently, the vehicle PCM may use the crankshaft position sensor data as a backup.
2) Check Engine Light Illumination
The illuminated check engine light is one of the first symptoms of a bad camshaft position sensor. However, your vehicle’s check engine light may come on because of various reasons. But in many cases, the main cause of the illuminated check engine light is a faulty camshaft position sensor.
When the check engine light of your vehicle activates, it is advisable to contact the nearest professional or use an OBD-II scanner at home to check the trouble codes such as P0340, P0341, and P0342.
Many people may overlook the check engine light, unaware that it could signify a more serious issue, including potential engine damage.
Read More: Causes of Check Engine Light Illumination
3) Car Jerking
If your camshaft position sensor starts to malfunction while you are driving, the engine may intermittently lose power, causing the vehicle to jerk or surge forward unexpectedly.
Your car usually jerks because of an incorrect fuel injection rate or the engine losing power while the car is moving.
Read More: Causes of Car Shaking and Vibration
4) Ignition Issues
As the camshaft sensor begins to fail, it starts to send the wrong signal to the vehicle’s powertrain control module. Eventually, the signal may become so weak that your start to observe different issues in your vehicle, such as poor ignition, poor fuel economy, or misfiring.
5) Poor Engine Performance
A faulty camshaft sensor may lead to a significant reduction in engine performance. This can be observable as reduced engine speed, idling, and frequent stalling, as well as reduced fuel efficiency.
It is crucial to promptly address the issues related to engine performance since they typically appear due to a faulty cam sensor. In some cases, your engine may enter Limp mode when the camshaft position sensor is malfunctioning.
6) Fuel System Issues
The cams sensor helps regulate the fuel entering the combustion chamber by sending signals to the vehicle’s PCM, which adjusts the timing and duration of fuel injection.
A faulty CMP sensor can’t perform this work efficiently, causing disruptions in the fuel system and leading to additional issues.
Read More: Fuel System Working and Parts
7) Engine Misfire
Engine misfiring is another common symptom of a faulty camshaft sensor. The engine misfiring usually occurs due to poor air-fuel mixture.
When your camshaft sensor sends wrong information to the PCM, it regulates the air-fuel ratio accordingly. By using wrong information, your PCM may signal the fuel injector to inject more fuel than the specified limit, causing misfiring.
8) Engine Stalling
The engine stalling is another common sign of a faulty camshaft position (CMP) sensor. This is because when your CMP sensor becomes faulty, your fuel injector doesn’t receive the necessary information to send fuel to the engine cylinder at the correct times. As a result, the engine loses power and begins to stall.
In some cases, the engine may enter limp mode, where the car remains in a single gear and cannot run more than a specific speed.
Read More: Causes of Limp Stalling
9) Poor Acceleration
The fuel injection problems caused by a malfunctioning camshaft sensor may ultimately impact the vehicle’s acceleration. This happens because the failing CMP sensor sends incorrect or irregular signals to the vehicle’s computer, affecting fuel injection rate and ignition timing.
When there is something wrong with the fuel injection rate and ignition timing, the throttle response is compromised, leading to poor acceleration.
10) Transmission Issues
Vehicle models with automatic transmissions may experience improper gear shifting if the camshaft position sensor is faulty. When this sensor goes bad, it may lock the transmission, and your vehicle will be unable to shift beyond a single gear. This often happens when the vehicle enters limp mode.
11) Rough Idling
Rough idling is also a symptom of a faulty camshaft position sensor. When the sensor goes bad, a rough idle may occur because of uneven air-fuel mixture combustion in the cylinders.
However, rough idling may also be caused due to a faulty exhaust gas recirculation (EGR) valve or idle fuel pump.
Read More: Why My Car Shuts Off While Driving
12) Failed Emissions Test
An underperforming engine may struggle to burn fuel efficiently, resulting in higher emissions. In such conditions, your vehicle will be failed to pass the emission test.
13) Fuel Smell
A malfunctioning camshaft sensor may indirectly cause unburned fuel to enter the exhaust system of your vehicle, which not only affects fuel economy but may also produce black smoke from the exhaust pipe. This unburned fuel emits a noticeable and potentially harmful smell.
14) Poor Fuel Economy
Poor fuel economy is also one of the clear symptoms of the bad camshaft position sensor. Although this is relatively rare, it is essential to check the trouble codes for any issues related to the camshaft sensor if you experience poor fuel economy.
Read More: Bad Crankshaft Position Sensor Symptoms and Causes
Causes of a Bad Camshaft Position Sensor
A camshaft position sensor may go bad due to one or more of the below-given causes:
- Insufficient maintenance of the vehicle
- Wear and tear
- Age of the sensor
- Physical damage
- Extremes temperature and heat
- Contamination and dirt
- Damaged connectors or wiring
- Moisture and corrosion
1) Wear and Tear
The wear and tear of the camshaft position sensor is one of the major causes of its failure. It may wear out with time, like other engine parts. The internal parts of the sensor may damage over time, eventually leading to sensor failure.
2) Physical Damage
Your sensor may be damaged due to engine work, engine overheating, bad PCM, accidents, or other physical impacts. Damage to the sensor casing or other internal parts may also cause the sensor failure.
3) Extremes Temperature and Heat
Higher temperature and pressure for a long time may lead to the failure of the camshaft position sensor. A high temperature may force the internal parts to expand, while a low temperature may cause brittleness or cracking.
4) Contamination and Dirt
Different contaminants such as debris, oil, and dirt may accumulate inside the sensor, which affects the ability of the sensor to precisely measure the camshaft’s position. These contaminants may cause incorrect signals or no signals at all.
5) Damaged Connectors or Wiring
The electrical connectors and wires that connect the camshaft position sensor to the PCM may become corroded, frayed, or damaged over time. This issue may cause weak signals, poor connections, or unresponsive sensor.
6) Moisture and Corrosion
When water or moisture enters the camshaft sensor or its electrical connections, it may produce corrosion. The corrosion may lead to sensor failure or poor connections. This issue is most common in highly humid environments or areas.
Camshaft Position Sensor Location
The location of the camshaft position sensor varies according to the vehicle make, model, and type of engine. The camshaft position sensor is usually located near the camshaft or cylinder head on most engines.
How to replace a Camshaft Position Sensor?
Follow the below-given steps to replace a camshaft psoiton sensor:
- Park your vehicle on a flat surface
- Turn off your vehicle engine
- Gather the necessary tools, such as a screwdriver, gloves, socket set, and ratchet.
- Disconnect the negative battery cable to prevent yourself from an electric shock.
- Find the camshaft position sensor. It is recommended to check the vehicle manual to find the exact position of your sensor. It is usually located near the camshaft.
- Remove the other components, such as coolant hoses or air intake systems, to easily access the sensor.
- Remove the tab on the sensor to remove the wires from the sensor.
- Use a socket or wrench to remove the mounting bolt that connects the sensor to the engine.
- Gently remove the sensor with a slight twist.
- Test the new sensor and install it according to the manufacturer’s instructions.
- Apply a small amount of oil to the O-ring of the new sensor.
- Reinstall all the components back in their original places.
- Reconnect the negative battery terminal.
- Perform a test drive to check the performance of the new sensor.
Camshaft Position Sensor Replacement Cost
The replacement or repair cost of the camshaft position (CMP) sensor varies according to vehicle model, labor cost, and the type of part brand.
The average replacement cost of the camshaft position sensor is from $80 to $270. The labor cost is from $20 to $130, while the part itself costs from $60 to $140.
The replacement cost of a CMP sensor in a luxury car may be higher. If you don’t replace the sensor yourself, the labor cost of replacement maybe $25 to $120.
| Labor Cost | $25 to $120 |
| Part Cost | $75 to $140 |
| Camshaft Position Sensor Replacement Cost | $80 to $270 |
FAQ Section
What does a bad camshaft sound like?
A faulty camshaft usually produces distinct noises that indicate there is an issue with the component. These sounds typically include popping, tapping, and ticking. Additionally, you may hear frequent backfiring as the engine’s cylinders misfire at varying RPMs.
What is the function of the camshaft position sensor?
The camshaft position sensor is used to monitor the position and rotational speed of the camshaft in an internal combustion engine. It sends its information to the powertrain control module (PCM), which utilizes this information to improve fuel injection and ignition timing, improving overall engine performance, emissions, and fuel efficiency.
Can I drive with a bad camshaft position sensor?
Driving with a faulty camshaft position sensor is not recommended, although it might still be possible. A bad sensor can cause your vehicle to perform poorly and may even prevent it from starting. While it’s unlikely to cause your vehicle to shut off, it’s still not recommended. It is best to replace the sensor immediately to avoid any potential issues.
How to reset a cam sensor?
Resetting a camshaft position sensor is not typically possible, as it is an engine part that delivers data about the camshaft to the PCM. If you are facing problems with the camshaft position sensor, it is recommended to diagnose and fix the issue, which may involve repairing, cleaning, or replacing the sensor.
How to clean a camshaft position sensor?
- Locate the camshaft position sensor.
- Disconnect the negative terminal of the battery.
- Disconnect the electrical connector and remove the cam sensor by using a screwdriver, socket, or wrench.
- Remove the solid contaminants from the sensor’s exterior by using a clean cloth or a soft-bristle brush. To remove oil or stubborn grime, use a small amount of isopropyl alcohol or electrical contact cleaner on the cloth or brush.
- Reinstall the sensor and reconnect the negative terminal of the battery.
- Perform a test drive to check the working of the cam sensor.
How long does a camshaft sensor last?
The cam sensor is built to last the life of the car, and there is no set maintenance schedule for when the camshaft position sensor should be replaced. It only needs to be replaced when it is damaged or bad.
What happens when a camshaft sensor goes bad?
As the camshaft sensor goes bad, your vehicle starts to produce different drivability issues such as poor acceleration, poor fuel economy, check engine light illumination, difficult engine starting, rough idling, ignition issues, car jerking, poor engine performance, misfiring, fuel smell and engine stalling. When your cam sensor goes bad, you should immediately contact a professional.
How many camshaft sensors does a vehicle have?
The number of camshaft position sensors in a vehicle varies according to the vehicle model and the engine’s configuration. Normally, a vehicle with a single camshaft contains one camshaft sensor, while a dual camshaft (DOHC) engine contains two camshaft sensors (i.e., one for each camshaft). Some modern vehicle models also have four camshaft position sensors, one for each camshaft.
Can a bad camshaft position sensor cause misfiring?
Yes, a bad camshaft sensor can cause misfiring, as it may provide incorrect information about the camshaft’s position, leading to improper ignition timing and engine misfires.
