Camshaft Position Sensor
2021 Honda Accord · 1.5L I4 Turbo
Sensor Type
hall-effect
Waveform Type
dc-square
Location
Rear of cylinder head near timing chain cover, mounted vertically on exhaust camshaft at transmission end of engine
Pins
3-pin connector
Idle Frequency
12.5 Hz
Timebase
50ms/div
Voltage Scale
2V/div
Trigger
2.5V, rising edge
Wiring
Blue/Yellow (signal), Black (ground), White/Blue (5V reference)
Expected Voltage Range
At Idle
0.2V to 4.8V
At Higher RPM
0.2V to 4.8V
Expected Pattern
4 pulses per camshaft revolution with varying widths for cylinder identification, square wave pattern synchronized with crankshaft at 1:2 ratio
Known-Good Waveform
Clean digital square wave cycling between 0.2V and 4.8V at half the frequency of the crankshaft sensor (12.5Hz at idle). The pattern shows 4 distinct pulses of varying widths per camshaft revolution used for cylinder identification. With VTC (Variable Timing Control) active, pulse timing will shift relative to crankshaft sensor but maintain clean transitions.
Common Failure Patterns
No signal or flat line at 0V or 5V, engine runs rough or won't start
Cause: Failed Hall effect sensor due to heat exposure or internal short, common after 80k+ miles
Intermittent signal loss during warm-up or under load, erratic idle
Cause: Cracked solder joints inside sensor from thermal cycling, loose connector due to missing lock tab
Diagnostic Tips
Compare cam sensor signal timing to crank sensor - should maintain proper phase relationship. Excessive phase shift indicates timing chain stretch which is increasingly common on these 1.5T engines above 80k miles. Check for oil dilution from direct injection fuel entering crankcase which accelerates chain wear.
Related Diagnostic Trouble Codes
P0340P0341P0342P0343P0344
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
Free, no signup. View all waveforms for this vehicle