P0343

What it means

P0343 means the engine control unit has detected a circuit high fault on camshaft position sensor A, on bank 1 or the single sensor fitted. The control unit saw the sensor signal voltage stay higher than expected, which points to a short to voltage, an open circuit or a faulty sensor. Without a valid camshaft signal the engine management cannot time fuelling and ignition accurately.

Symptoms

• Engine cranks but is hard to start or will not start
• Engine misfires or runs roughly
• Reduced power or the car going into limp mode
• Engine stalling unexpectedly
• Poor fuel economy
• Malfunction indicator lamp on

Possible causes

• Faulty camshaft position sensorlikely
• Damaged, chafed or shorted wiring in the sensor signal circuit, such as a short to voltagelikely
• Corroded, loose or contaminated connector at the sensor or control unitlikely
• Open circuit in the signal or ground wire causing a high readingpossible
• Damaged or contaminated reluctor or trigger wheel, or incorrect sensor air gap or fittingpossible
• Low or unstable sensor supply voltage from a fault in the power feed or a weak batterypossible
• Fault within the engine control unitrare

How to diagnose

1. Read all stored and pending codes and note freeze frame data such as engine speed, load and temperature when the fault set
2. Check for related codes, especially crankshaft position or timing correlation codes, and for battery or charging faults
3. Visually inspect the sensor, its wiring harness and connector for chafing, oil contamination, heat damage, corrosion and bent or pushed-back pins
4. Check the sensor is securely fitted, with an undamaged seal and no debris or metal particles on its tip
5. With the engine cranking or running, view live data for camshaft and crankshaft signal presence and engine speed
6. Check the sensor supply, ground and signal wiring with a multimeter against the manufacturer's wiring diagram, looking for shorts to voltage and open circuits
7. Inspect the signal on an oscilloscope if available and compare it to a known good pattern for that engine
8. Inspect the reluctor or trigger wheel and confirm camshaft timing is correct, following the procedure for the specific engine

How to fix

• Replace the camshaft position sensor if it is faulty or its signal is out of specification
• Repair or replace damaged wiring and clear any short to voltage or open circuit
• Clean, repair or replace corroded or damaged connectors and terminals
• Correct the sensor fitting, replace its seal and clean off contamination
• Repair or replace a damaged trigger wheel, or correct camshaft timing, as the model requires
• Correct any supply voltage or battery fault, and only consider the control unit after all other causes are ruled out

Can I keep driving?

Nearby codes

• P0342GenericCamshaft Position Sensor A Circuit Low Bank 1 or Single Sensor
• P0344GenericCamshaft Position Sensor A Circuit Intermittent Bank 1 or Single Sensor