P0343: Camshaft Position Sensor A Circuit High Input (Bank 1)
The P0343 code indicates that the Engine Control Module (ECM) has detected a voltage signal from the camshaft position sensor that is higher than the expected range. This sensor monitors the position of the camshaft relative to the crankshaft to optimize fuel injection and ignition timing. A high input condition can be caused by a faulty sensor, wiring issues, or a problem with the sensor's reference voltage or ground circuit. This code is specific to Bank 1, which is the side of the engine containing cylinder #1.
01. Most Common Causes
- Faulty camshaft position sensor
- Short to voltage in the sensor circuit
- Damaged wiring or connector
- Corroded or loose electrical connections
- Faulty ECM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine may run rough or misfire
- Hard starting or stalling
- Reduced fuel economy
- Engine may not start at all
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect the camshaft position sensor and wiring for damage, corrosion, or loose connections.
Step 3: Test the sensor's voltage supply (typically 5V) and ground circuit with a multimeter.
Step 4: Check the sensor's signal voltage while cranking the engine; it should pulse between 0V and 5V.
Step 5: If signal is stuck high, replace the sensor. If wiring is faulty, repair as needed.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with P0343 as it can cause poor engine performance, stalling, or no-start conditions. Have it diagnosed and repaired promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for a DIY sensor replacement, or $150 to $300 if done by a shop including labor.