P0343
Camshaft Position Sensor Circuit Low Input
Powertrain Ignition System Camshaft Sensor Signal 🟡 Moderate — Fix within a week
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What This Actually Means
In plain language — no jargon

The camshaft position sensor is sending a voltage signal that's too low, like a weak radio signal that's hard to hear. The engine computer can't properly time the fuel injection and ignition, causing performance problems.

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Symptoms You May Notice
3 known symptoms for this code
Check Engine Light illuminated
Rough idle or stalling
Reduced fuel economy and hesitation during acceleration
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECM monitors the analog voltage output from the camshaft position sensor, which typically cycles between 0–5V as the camshaft rotates. A 'low input' fault occurs when the sensor voltage drops below the minimum expected threshold, indicating either a weak signal, damaged wiring, or failing sensor.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Sensor Output Voltage 0.5–4.5V (dynamic range) Below 0.2V or no signal detected
Signal Rise Time 10–100ms transition Excessively slow or no transition
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Wiring harness and connectors
Inspect the sensor connector and wires for corrosion, loose pins, or damage; clean and reseat the connection.
2
Camshaft Position Sensor
Test sensor resistance with a multimeter; replace if out of spec or if voltage remains low after harness repair.
3
ECM or wiring to ECM
If sensor and harness are good, test the ECM signal pin; damaged ECM traces may require professional repair.