P0343 Camshaft Position Sensor “A” Circuit Low

OBD-II Trouble Code - P0343 - Data Sheet

Camshaft position sensor A circuit high input (bank 1).

DTC P0343 is related to the vehicle's timing system and the camshaft position sensor, which monitors the rotation of the camshaft to send data to the engine's computer so it can calculate the appropriate amount of fuel and ignition.

What does trouble code P0343 mean?

This is a Generic Transmission Diagnostic Trouble Code (DTC), which means it covers all makes / models from around 2003 onwards.

The code seems to be more common on VW, Kia, Hyundai, Chevrolet, Toyota, and Ford vehicles, but it can affect cars of any brand. The specific troubleshooting steps vary from vehicle to vehicle.

These cars can have one camshaft in the block or one (SOHC) or two (DOHC) overhead camshafts, but this code strictly takes care that there is no input signal from bank 1 camshaft position sensor(s), usually to start the engine . This is an electrical circuit failure. Bank #1 is the engine block that houses cylinder #1.

The PCM uses the camshaft position sensor to tell it when the crankshaft sensor signal is correct, when the given crankshaft position sensor signal is synchronized with cylinder # 1 for timing, and it is also used to synchronize the fuel injector / start injection.

Codes P0340 or P0341 can also be present at the same time as P0343. The only difference between these three codes is how long the problem lasts and the type of electrical problem that the sensor / circuit / motor controller is experiencing. Troubleshooting steps may vary depending on the manufacturer, type of camshaft position sensor and wire colors.

Symptoms

Since a faulty camshaft position sensor can cause the engine to deliver the wrong amount of fuel and/or spark, a P0343 code may be likely to occur under poor driving conditions. Typically, code leads to open, unstable, deadlock, or inconsistent issues.

Symptoms of a P0343 engine code may include:

• Check engine indicator for
• Rocking or bloating
• Goes off, but may restart if problem is inconsistent.
• May work fine until restarted; then won't restart

Possible causes of error З0343

Typically the camshaft position sensor becomes contaminated with oil or moisture, resulting in poor ground or voltage in the signal wiring. However, other likely causes include:

• Faulty camshaft position sensor
• Faulty ground wiring
• Power wiring fault
• Defective starter
• Weak or dead battery
• Faulty engine computer
• Open in the ground circuit to the camshaft position sensor
• Open in the signal circuit between the camshaft position sensor and the PCM
• Short circuit to 5 V in the signal circuit of the camshaft position sensor
• Sometimes the camshaft position sensor is faulty - internal short circuit to voltage

Diagnostic and repair procedures

A good starting point is always to find a Technical Service Bulletin (TSB) for your specific vehicle. The vehicle manufacturer may have a flash memory / PCM reprogramming to fix this problem and it's worth checking it out before you find yourself on the long / wrong path.

Then find the camshaft and crankshaft position sensors on your specific vehicle. Since they share power and ground circuits, and this code focuses on the power and ground circuits of the CMP sensor, it only makes sense to test them to see if there is damage to any of them.

An example of a photo of a camshaft position (CMP) sensor:

Once detected, visually inspect the connectors and wiring. Look for scuffs, scuffs, exposed wires, burn marks, or molten plastic. Disconnect the connectors and carefully inspect the terminals (metal parts) inside the connectors. See if they look rusty, burnt, or perhaps green compared to the usual metallic color you're probably used to seeing. If terminal cleaning is required, you can purchase electrical contact cleaner at any parts store. If this is not possible, find 91% rubbing alcohol and a light plastic bristle brush to clean them. Then let them air dry, take a dielectric silicone compound (the same material they use for bulb holders and spark plug wires) and place where the terminals make contact.

If you have a scan tool, clear the diagnostic trouble codes from memory and see if the code returns. If this is not the case, then there is most likely a connection problem.

If the code returns, we will need to test the sensor and associated circuits. There are usually 2 types of camshaft position sensors: Hall effect or magnetic sensor. You can usually tell which one you have by the number of wires coming from the sensor. If there are 3 wires from the sensor, this is a Hall sensor. If it has 2 wires, it will be a magnetic pickup type sensor.

This code will only be set if the sensor is a Hall effect sensor. Disconnect the harness from the CMP sensor. Use a digital volt ohmmeter (DVOM) to check the 5V power supply circuit going to the sensor to make sure it is on (red wire to 5V / 12V power supply circuit, black wire to good ground). Use the wiring diagram or diagnostic table to check if this sensor is powered by 5 or 12 volts. If the sensor is 12 volts when it should be 5 volts, repair the wiring from the PCM to the sensor for a short to 12 volts or possibly a faulty PCM.

If this is normal, with the DVOM, make sure you have 5V on the CMP signal circuit (red wire to the sensor signal circuit, black wire to good ground). If there is no 5 volts on the sensor, or if you see 12 volts on the sensor, repair the wiring from the PCM to the sensor, or again, possibly a faulty PCM.

If everything is in order, check that each sensor is properly grounded. Connect a test lamp to the 12 V battery positive (red terminal) and touch the other end of the test lamp to the ground circuit that leads to the camshaft sensor circuit ground. If the test lamp does not light up, it indicates a faulty circuit. If it does light up, wiggle the wire harness going to each sensor to see if the test lamp blinks, indicating an intermittent connection.

Associated Camshaft DTCs: P0340, P0341, P0342, P0345, P0346, P0347, P0348, P0349, P0365, P0366, P0367, P0368, P0369, P0390, P0391, P0392, P0393. P0394.

COMMON ERRORS WHEN DIAGNOSING CODE P0343

The most common error when dealing with a P0343 circle is around faulty replacement sensors. It is important to use high quality replacement parts and avoid cheaper or used options. Since some sensors also jam due to oil leaks, it is a good idea to fix any nearby leaks so the problem doesn't persist.

HOW SERIOUS CODE P0343 IS?

Since the camshaft position sensor is very important for fuel injection in a modern car, a P0343 code can seriously affect the way a car is driven. It is advisable to refer to this code as soon as possible.

WHAT REPAIRS CAN FIX CODE P0343?

The most common repair for P0343 is as follows:

• Replacing the camshaft position sensor
• Replacing damaged cables and connectors
• Cleaning ground wires
• Repair an oil leak nearby

ADDITIONAL COMMENTS TO BE AWARE OF CODE P0343

Codes P0343 appear on Chevrolet, Kia, Volkswagen and Hyundai models - usually models from 2003 to 2005. It is also not uncommon for a P0343 code to cause additional trouble codes as a result.

How to Fix P0343 Engine Code in 3 Minutes [2 DIY Methods / Only $9.24]

Need more help with your p0343 code?

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