Will a bad crank sensor throw a code?
Yes, a bad crank sensor can definitely throw a trouble code. The crank sensor is a critical component in a vehicle's engine management system, and if it fails or malfunctions, it can trigger a diagnostic trouble code (DTC) to be set in the vehicle's onboard computer.
What is a Crank Sensor and How Does it Work?
The crank sensor, also known as the crankshaft position sensor, is responsible for monitoring the rotation of the engine's crankshaft. It sends signals to the vehicle's engine control unit (ECU) about the crankshaft's position and speed. This information is essential for the ECU to properly time the ignition and fuel injection events, ensuring the engine runs smoothly and efficiently.
The crank sensor is typically located near the crankshaft, often on the engine block or the transmission housing. It uses a magnetic field to detect the rotation of the crankshaft and converts this information into electrical signals that the ECU can interpret.
How Can a Bad Crank Sensor Cause a Trouble Code?
If the crank sensor fails or provides inaccurate information to the ECU, it can result in a variety of problems, including:
- Misfiring or rough idling: The ECU relies on the crank sensor data to properly time the ignition and fuel injection. If the sensor is malfunctioning, the engine may misfire or run rough, especially at idle.
- Poor engine performance: A bad crank sensor can cause the engine to run inefficiently, leading to reduced power, acceleration, and fuel economy.
- Illuminated check engine light: When the ECU detects an issue with the crank sensor, it will set a diagnostic trouble code and illuminate the check engine light on the dashboard.
The specific trouble code set will depend on the nature of the crank sensor problem, such as a sensor signal that is intermittent, erratic, or out of range.
Diagnosing and Replacing a Bad Crank Sensor
If a diagnostic trouble code related to the crank sensor is set, the first step is to use an OBD-II scanner to read the code and determine the nature of the problem. From there, a technician can perform further testing, such as checking the sensor's wiring, voltage, and resistance, to isolate the cause of the issue.
If the crank sensor is found to be faulty, it will need to be replaced. This is typically a straightforward repair, but the specific process can vary depending on the vehicle make and model. In some cases, the sensor may be integrated into a larger component, such as the crankshaft position sensor assembly, which would need to be replaced as a unit.
Addressing a bad crank sensor in a timely manner is important to prevent further damage to the engine and maintain proper vehicle performance and fuel efficiency.
How do I know if my crank sensor is bad?
A bad crankshaft sensor can cause the check engine light to come on, lead to engine stalling or rough idling, and result in difficulty starting the car. Other symptoms include poor acceleration, misfires, and reduced fuel economy. You can confirm a faulty sensor by using an OBD2 scanner to check for trouble codes or by performing a multimeter test on the sensor itself.
Common symptoms
- Check Engine Light: This is one of the most common and earliest signs of a faulty sensor, as the vehicle's computer will detect an issue with the signal.
- Stalling: The engine may randomly shut off while you are driving or idling, which is a serious safety concern.
- Rough idling and vibration: The engine may shake or run unevenly, especially at a stop.
- Difficulty starting: The engine may crank longer than usual before starting, or it may not start at all if the sensor fails completely.
- Poor acceleration: You may notice a lack of power when trying to accelerate or a hesitation and jerking motion.
- Engine misfires: The engine may misfire, which can sometimes be accompanied by a flashing check engine light.
- Reduced fuel economy: The engine's computer may be sending the wrong signals for fuel injection and timing, leading to a noticeable drop in gas mileage.
- Unusual exhaust smells: In some cases, the incorrect timing can lead to incomplete combustion, causing unusual smells like sulfur or raw gasoline from the exhaust.
How to diagnose
- Use an OBD2 scanner: A mechanic can use an OBD2 scanner to read diagnostic trouble codes from the engine's computer, which may point to a crankshaft sensor issue (e.g., P0335).
- Perform a multimeter test: A technician can test the sensor's resistance value with a multimeter to determine if it is functioning correctly.
What code will a bad camshaft sensor throw?
A "bad camshaft position sensor code" refers to a diagnostic trouble code (DTC) like P0340 indicating a problem with the camshaft position sensor or its circuit. Common symptoms include a flashing check engine light, difficulty starting, rough idling, stalling, poor acceleration, and engine misfires. The problem can stem from a faulty sensor, damaged wiring, a poor electrical connection, or, less commonly, internal engine timing issues.
Common DTCs
- P0340: Camshaft Position Sensor "A" Circuit Malfunction
- P0341-P0344: Indicate a malfunction in the camshaft position sensor circuit, often related to a specific bank or an intermittent signal
- P0345: Camshaft Position Sensor "A" Circuit (Bank 2)
Symptoms of a bad camshaft position sensor
- Check engine light is on
- Vehicle may not start or is difficult to start
- Engine may stall, especially while driving or idling
- Rough idling
- Misfiring
- Loss of power or poor acceleration
- Poor fuel economy
- Transmission shifting problems
This video explains the symptoms of a bad camshaft position sensor and how to test it: 58sECU TESTINGYouTube · May 16, 2023
Potential causes
- Faulty sensor: The sensor itself is damaged or worn out.
- Wiring issues: The wiring or connectors are damaged, broken, or have a poor connection.
- Internal engine problems: In some cases, issues with the timing chain or belt can cause the sensor to get abnormal readings.
- Failed Powertrain Control Module (PCM): Though rare, a malfunctioning PCM can also cause this code.
This video shows how to test the camshaft position sensor wiring: 1mEasyAutoFixYouTube · Jul 8, 2024
What to do
- Diagnose the issue: Use an OBD-II scanner to confirm the specific trouble code.
- Inspect the wiring and connections: Visually inspect the sensor and its wiring for any obvious damage or loose connections.
- Test the circuit: A mechanic can test the circuit voltage with a multimeter to ensure proper power flow.
- Replace the sensor: If the sensor is faulty, replace it. This often resolves the issue.
- Seek professional help: If the problem persists, it may be an internal engine issue, and professional diagnosis is recommended.
Will a car start with a bad crank position sensor?
A car may or may not start with a bad crankshaft sensor, depending on the severity of the failure. A failing sensor can cause symptoms ranging from difficulty starting, stalling, and rough idling to complete no-start conditions. If the sensor fails completely, the engine will not start because the computer won't know when to time the spark and fuel injection.
This video explains the symptoms of a bad crankshaft position sensor, including starting issues: 1mEasyAutoFixYouTube · Feb 25, 2023
Why a car may not start
- Loss of timing information: The crankshaft sensor tells the engine's computer (PCM) the crankshaft's position and rotational speed. This information is critical for timing when to ignite the fuel-air mixture.
- No spark or fuel: Without a good signal from the sensor, the PCM can't correctly time the spark plugs or fuel injectors, meaning the engine won't run, explains this YouTube video.
- Complete failure: If the sensor fails completely, it can prevent the engine from starting at all, says Reddit users.
Other symptoms of a failing sensor
- Difficulty starting: The engine may crank for a longer time before starting, or may require several attempts.
- Stalling: The engine may stall while driving or when coming to a stop.
- Rough idling and misfires: The engine may run roughly or have misfires.
- Poor acceleration: The vehicle may hesitate or feel jerky when you press the gas pedal.
- Check engine light: The dashboard's check engine light will likely come on.
You can also watch this video to learn how to test a crankshaft and camshaft position sensor: 49sRatchets And WrenchesYouTube · Aug 4, 2015
What to do
- If you suspect a bad crankshaft sensor, it's best to get it inspected and replaced by a mechanic as soon as possible to avoid being stranded.
- You may be able to start the car if the sensor is only partially failing or is dirty, but a complete failure can prevent it from starting at all.
What happens if I unplug the crank sensor?
What Happens If You Unplug a Crank Sensor? Unplugging a crank sensor can cause serious issues with the engine's performance, and may even lead to complete engine failure. This isn't recommended.
