Code
P0340
MITSUBISHI
P — Powertrain
Camshaft position sensor
Views:
UK: 19
EN: 67
RU: 42
AI status
Completed
Completed
100%
Causes
- Faulty camshaft position sensor (Hall or VR type)
- Damaged wiring harness or connector (open, short to power/ground, corrosion)
- Poor sensor reference voltage or ground (ECU or wiring issue)
- Incorrect cam/crankshaft timing (stretched/failed timing belt or chain)
- Intermittent connector contact from oil or vibration
- Faulty PCM/ECM (rare)
Symptoms
- Malfunction Indicator Lamp (MIL) / Check Engine Light on
- Hard starting or failure to start
- Engine stalls or cranks but won’t start
- Rough idle, misfire or reduced power
- Poor fuel economy
- Intermittent loss of power or surging
What to check
- Retrieve freeze frame and stored codes with a scan tool and note conditions (engine speed, temperature)
- Check for additional related codes (crank sensor, timing, misfire)
- Visually inspect sensor and connector for oil, corrosion, broken pins, or damaged insulation
- Wiggle test wiring/connector while monitoring live cam sensor signal for intermittency
- Measure reference voltage and ground at the sensor connector with key on (typically ~5V reference for Hall sensors)
- Check signal output with oscilloscope (preferred) or multimeter while cranking/running
Signal parameters
- Hall‑type expected: 0–5 V square wave (signal switches between ~0 V and ~5 V); reference usually 5 V; frequency increases with engine speed
- VR‑type expected: AC sine/alternating signal; amplitude increases with engine speed (tens to hundreds of millivolts to volts)
- At idle: Hall sensor switching frequency low but present; VR sensor amplitude typically >100–200 mV peak-to-peak at idle (varies by vehicle)
- Signal duty cycle for Hall sensors commonly near 40–60% depending on cam tooth geometry
- No signal or erratic waveform indicates open/shorted sensor circuit, poor ground, or failed sensor
Diagnostic algorithm
- Connect a scan tool, confirm P0340 and any related codes; record freeze frame data
- Visually inspect cam sensor and harness for obvious damage, oil intrusion, or loose connector; repair as needed
- With key ON (engine off) measure reference voltage and ground at the sensor connector; reference should be present (commonly ~5 V for Hall sensors)
- Backprobe signal terminal while cranking/running. Check for correct waveform with oscilloscope. If no scope, check for pulsed voltage with a multimeter or test light (less reliable)
- If no reference or ground, trace wiring back to ECU and repair short/open/corrosion; check fuse and ECU pins
- If reference and ground present but no signal, swap or bench‑test sensor (compare resistance for VR or inspect Hall sensor switching with known good unit)
- Perform wiggle test on harness while monitoring signal for intermittent faults
- If signal present but timing correlation to crank is wrong, inspect timing belt/chain, camshaft position (timing variable actuator), and repair timing components as required
- After repair or sensor replacement, clear codes, perform a test drive and monitor live data for proper cam/crank correlation and that P0340 does not return
- If all wiring and sensor check good and problem persists, consider ECU diagnosis or replacement as last resort
Likely causes
- Damaged sensor wiring or dirty/corroded connector at the sensor
- Failed camshaft position sensor
- Loss of sensor reference power or ground from wiring or ECU
- Timing belt/chain jump or worn timing components causing no cam signal correlation
Fault status
Status
P0340 indicates the engine control module detected an abnormal or missing signal from the camshaft position sensor circuit. This can prevent the PCM from knowing camshaft position for timing control, causing no‑start, stalling, misfires, or limp-home behavior until the underlying wiring, sensor, timing, or control issue is repaired.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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