P0340 - Camshaft Position Sensor "A" Circuit (Bank 1 or Single Sensor)
System
Powertrain (Engine & Gearbox)
Technical Description
The ECM detects missing or corrupted signal pulses from Camshaft Position Sensor 1 (Bank 1). CMP signal is required to synchronize cylinder 1 compression stroke for sequential injection and VVT control.
Multimeter Test Points & Nominal Values
| Test Point / Component | Measurement | Nominal Target Range | Test Condition |
|---|---|---|---|
| Hall Effect Supply Voltage | Voltage (V) | 4.95 - 5.05 V (or 12.0 V) | Ignition ON |
| Signal Amplitude (Square wave) | Voltage (V) | 0.2 V (low) / 4.8 V (high) | Engine idling |
| Ground Circuit Resistance | Resistance (Ω) | < 0.5 Ω | Sensor ground to chassis |
Ignition ON
Engine idling
Sensor ground to chassis
Oscilloscope Waveform Analysis
20 ms/div, 2 V/divPossible Causes
Faulty Camshaft Position Sensor (CMP)
Stretched timing chain or skipped timing belt tooth
Wiring harness damage or terminal corrosion
Sticking VVT camshaft phaser / oil control solenoid
Symptoms
3
Recommended Solution
Verify power feed and ground at sensor connector.
Scope CMP against CKP to detect timing chain stretch.
Replace CMP sensor or service timing chain/belt if out of phase.
Mechanic's Tip
When the CMP fails, the ECM must guess compression stroke using trial-and-error crankshaft acceleration, causing a characteristic 3-4 second extended cranking time.
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