What is P0303 DTC? Common Symptoms, Causes, and Solution
Usually, the vehicles have 4, 6, or 8 cylinders, and the greater the engine’s power is produced. However, it is necessary for the engine to time the ignition in these cylinders for effective power generation, or else the car will face jerks and power loss.
The following are the key takeaways from this article:
P0303 is a severe-intensity engine fault code that indicates a misfiring engine cylinder 3.
The possible causes of P0303 include low-quality fuel, faulty fuel injectors, faulty crankshaft and crankshaft sensors, vacuum leakage, and a leaking gasket.
The common symptoms of P0303 include a rotten fuel smell from exhaust, lack of power, and jerks during acceleration.
The common solutions include hard resetting the DTC, changing the sparkplugs, changing the leakage components, and changing the gaskets and faulty injectors.
The cost to resolve this issue can be as low as $20 (in case of crankshaft sensor failure) and as high as $2000 to replace the faulty fuel injectors.
Introduction
Effective ignition is necessary for power generation by the engine. An air-fuel mixture is burned and compressed within the cylinders. The moving of pistons accomplishes this burning and compression of fuel, and the fuel is ignited at a specific time (2). However, if any one cylinder misfires, there will be a lag in power generation, and you might experience jerking during acceleration (1).
P0303 is a serious engine fault code indicating that cylinder number 3 is misfiring. It means that cylinder three is not performing proper combustion for many reasons.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
This article will shed light on the reasons, symptoms, and possible solutions of P0303 DTC.
How to Read P0303 DTC
The following table has read every character of P0303 DTC (2):
Number of Character
Specific Character
What does it Signify
First
P
The problem lies within the powertrain part of the vehicle. This means that the engine, transmission, or fuel system can malfunction
Second
0
This means that the code is standardized, so the SAE manual can be used further to interpret the code instead of the instruction manual.
Third
3
This number illustrates the problem within the vehicle’s engine cylinders.
Fourth and Fifth
03
The specific fault index is 03, indicating that engine cylinder number 3 is misfiring.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
P0303 means that the problem lies within the powertrain and is SAE standardized. Further, the DTC indicates that cylinder number 3 is misfiring, resulting in less power generation from the engine.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
Causes of P0303 DTC
Defected Crankshaft or Crankshaft Sensor
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
The major reason for the engine code P0303 is the defective camshaft sensor. The camshaft sensor is an important part of the car’s engine. It controls the fuel intake and fume release from the exhaust system.
A camshaft sensor checks the camshaft position and speed and sends the gathered information to the engine control system. This helps determine the required amount of fuel and predicts the spark’s time in the engine (5). However, a damaged camshaft can impact the engine’s performance as the wrong information is sent to the engine control module and the wrong prediction regarding the required fuel amount. Thus, more fuel is consumed, and engine code P0303 is shown as a warning indication.
Besides, the crankshaft sensor is also an essential part of the vehicle. The role of the crankshaft sensor is to maintain the position and movement of the crankshaft (2). The damaged crankshaft sensor can turn on the engine code P0303. The damaged crankshaft sensor sends inaccurate data to ECU, and ultimately the vehicle fails to travel the high peaks.
Low Fuel Pressure and Vacuum Leakage
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
Another major cause of the engine code P0303 is the low fuel pressure in the engine. The low fuel pressure will lead to a rough and idle engine. Also, engine misfires in the cylinders can occur.
Due to the low fuel pressure in the engine, the vehicle will fail to travel long distances because less power is generated in the engine due to the less fuel. As a result, the fuel pump becomes weak, and the vehicle fails to accelerate with speed (5). Thus, as a result, engine code P0303 is indicated.
Also, another reason the engine code P0303 is the vacuum leakage. The vacuum leakage will make the engine rough and noisy, and as a result performance of the engine becomes poor. This is because the air-to-fuel ratio is unbalanced in the engine, and the temperature is raised than normal. These issues turn the engine light on due to code P0303 (1).
Leaked Gasket
Moreover, the head gasket plays an essential role in the car, and the damaged head gasket can increase the overall temperature of the engine (5).
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
Due to the leak head gasket, it becomes difficult for the engine to generate the required amount of power, and the car face issues traveling high distances.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
Also, due to the leaking head gasket, the coolant level in the engine drops, and the engine’s temperature suddenly increases, which impacts the engine’s performance.
Low-Quality Fuel
Low-quality fuel can cause misfiring in one cylinder. Low-quality fuel generally contains carbon particles that result in engine knocking as these carbon particles are stuck between different engine parts.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
The carbon particles can also be stuck in the fuel injector, impacting the fuel flow from these injectors in the cylinder. This can cause a lean condition in the cylinder that can eventually result in the misfiring of that particular cylinder.
Thus, it is recommended to consult the vehicle’s instruction manual to fill in the proper fuel (4). Some vehicles requiring high octane can also misfire when filled with ordinary/low-quality fuel.
Faulty Fuel Injectors
As the name indicates, fuel injectors are responsible for injecting the right fuel stream into the engine at the right time. Depending on engine requirements, ECU directs the fuel injectors to inject the fuel stream (2). But sometimes low-quality fuel or other dust particles can trap in the fuel injectors, impacting their ability to inject the right quantity of fuel into the cylinder.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
This can cause a lean condition inside the particular cylinder as the proportion of air would be greater in the air-fuel mixture. In this case, the cylinders will misfire, and the vehicle will show less power of jerky acceleration.
Symptoms of P0303 DTC
Following are a few symptoms of P0303 DTC:
Rotten Smell from Exhaust
The major symptom of engine code P0303 is the rotten egg-like smell from the vehicle’s exhaust system. This happens because the engine’s performance of the catalytic converter becomes poor due to the unbalanced ratio of the air and fuel in the engine.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
This ratio is usually disturbed because of vacuum leakage. The mixture moves in the engine and is one of the major reasons for the catalytic converter blockage. This deposits the nitrides and sulfides in the catalytic converter. As a result, the rotten egg-like smell is released from the exhaust system. Also, black-colored smoke is observed (4). These symptoms indicate an issue with the engine’s cylinders, and the check light is indicated due to the engine code P0303.
Rough and Shaky Engine
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
Another symptom of the engine code P0303 is the rough performance of the engine. The vehicle’s engine may become damaged and idle for various reasons, such as a misfire in the cylinder.
The rough and idle performance of the engine is usually observed due to vacuum leakage. Also, the lower fuel pressure in the engine impacts the engine’s overall performance because of the limited amount of power generated (3). Due to less power, the car fails to accelerate speedily, and harsh noises are observed from the engine.
Lack of Power
The generation of less power indicates that the engine light on the dashboard is indicated due to the code P0303. This is due to the damaged camshaft and crankshaft sensors.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
The damaged sensors gather the wrong information and send it to the car’s electronic control system. Thus, the wrong pieces of information reduce fuel efficiency and power, affecting the overall power generation. Thus, the car fails to accelerate at high speeds.
Furthermore, the damaged head gaskets also become the reason for poor power generation as the overall temperature of the engine becomes high due to the limited amount of coolant. As a result, less power is generated due to the poor efficiency of the engine. These issues indicate the engine code P0303 in the vehicle.
Solution of P0303
Following are a few common solutions of P0303:
Reset the DTC and Test Drive
Suppose you are not experiencing any common symptoms of P0303 DTC, and the check engine light is on. In that case, it is recommended to reset the DTC and test drive the vehicle. In this case, connect the hand-code reader with the OBDII module to check the DTC (4). There it would provide an option to reset the DTC. Reset the DTC and test drive your vehicle to ensure the check engine light does not illuminate again. If it happens, you should take the car to a nearby service center to resolve the issue.
Change the Sparkplugs
The sparkplug is another important component in the car’s engine that ignites the air-fuel mixture resulting in combustion. In some cases, faulty sparkplugs can also result in engine misfire, so consider changing the sparkplugs at home. The sparkplugs can be ordered online, and changing them at around 30,000 miles is recommended (4). For this purpose, remove the sparkplug wire and the coil on the plug (COP). Unscrew the sparkplug using the keyset and screw the new sparkplugs. Ensure that the new sparkplugs are according to the manufacturer’s specifications for optimum engine performance. Put on the COP and sparkplug wire back and test drive the vehicle.
Change the Leakage Components
Leakage in the holes and tubes can result in larger air entering the engine cylinder. However, the MAF sensor does not detect this and sends the wrong information to ECU, resulting in a lean mixture inside the cylinder. Generally, a cylinder misfires when the lean mixture enters the cylinder frequently. Thus, it is recommended to visually inspect the components and change any cracked components to avoid leakage.
Change the Gasket or Faulty Fuel Injectors
The final solution to this problem is to change the leaking gasket or the faulty fuel injectors. Unfortunately, these components are quite complex and can only be comprehended by experts. Thus, it is recommended to take the car to a professional mechanic to get these components replaced timely to avoid any further engine damage.
Cost to Resolve P0303 DTC
The following table illustrates the severity and the cost required to resolve the P0303 DTC:
Common Issues
Critical Level
Cost Required to Resolve the Issue
Sparkplug Issues
Intermediate: You can drive for medium distances with this problem. However, improper combustion will result in engine component damage.
$66-250 to replace the sparkplugs depending upon the number of sparkplugs to be replaced.
Vacuum Leak
Low: You can drive for even long distances with this issue
$20-50 to replace the damaged intake pipes and hoses
Fuel Injectors
High: Driving along with faulty fuel injectors can damage the internal engine components
$1500-1900 to replace the faulty fuel injectors
Ignition Coils
High: Driving along with faulty ignition coils can result in the engine seizing
$230-640 to replace ignition coils
Defected Crankshaft and Crankshaft Sensors
High: Driving along with a defective crankshaft can result in engine failure
$150-250 to replace defective crankshaft, $25-40 to replace the crankshaft sensor.
Labor Cost
–
$20-200 to replace the faulty components.
Conclusion
To conclude, P0303 is a serious engine fault code that indicates a misfire in cylinder number 3. The possible causes of this engine fault code include low-quality fuel, faulty fuel injectors, faulty sparkplugs, crankshaft and crankshaft sensors, and vacuum leakage. So, you feel less power in your vehicle and jerky acceleration while driving. In that case, the DTC can be P0303 indicating some problem in the engine cylinders.
The basic step to deactivate a limp mode is to stop the vehicle for around 10 minutes. This will rest the engine, and the in-build car computer will disable every mechanism. Try driving the vehicle after resting the engine. Suppose the vehicle RPM is at most 3000. In that case, it is a sign of a serious issue, and you should take your car to a professional mechanic to resolve the issue.
Heating in the Gasket can be a cause of leakage. In addition, pre-ignition trouble could result in fuel combustion at the wrong time, which sends enormous pressure into the cylinder head, causing perforation and damage to the gasket. This will eventually result in misfiring cylinders.
The DTC code indicates the exact cylinder number that is misfiring. Further, symptoms such as jerks while accelerating and less power from the engine indicate a misfiring cylinder. This should be resolved as early as possible to avoid any further engine damage.
