Fuel Injector
2021 Honda Accord · 1.5L I4 Turbo
Sensor Type
inductive
Waveform Type
pulse-width
Location
Direct injection high-pressure injectors mounted in cylinder head, fed by high-pressure fuel rail on intake side
Pins
2-pin connector
Idle Frequency
25 Hz
Timebase
2ms/div
Voltage Scale
50V/div
Trigger
20V, rising edge
Wiring
Red (12V battery supply from fuel injection relay), individual ECM control wires - Blue/Yellow, Yellow/Green, Green/Black, Black/Red for cylinders 1-4
Expected Voltage Range
At Idle
-80V to 95V
At Higher RPM
-100V to 110V
Expected Pattern
Current ramp phase to peak voltage 80-100V over 0.3ms, hold phase at battery voltage, cutoff spike to -80 to -100V with damped oscillations
Known-Good Waveform
Initial peak inductive spike to 80-100V during solenoid opening (peak and hold driver circuit), followed by hold phase at ~14V battery voltage for injector pulse duration of 0.8-2.5ms at idle. Sharp cutoff spike to -80 to -100V when ECM cuts ground circuit, followed by 2-3 clean damped oscillations returning to baseline. Pulse width increases under load and boost.
Common Failure Patterns
Reduced peak voltage below 60V or weak negative spike below -50V
Cause: High resistance in injector coil (normal 11-13Ω, failed >18Ω), corroded connector, or weak driver circuit
Excessive hash during hold phase or irregular oscillations at cutoff
Cause: Injector sticking mechanically, internal coil breakdown, or contaminated fuel causing restriction
Diagnostic Tips
The 1.5T uses Bosch direct injectors operating at 2000-2500 PSI. Carbon buildup on intake valves is extremely common due to no port fuel wash - compare injector pulse widths as ECM compensates with longer duration on affected cylinders. High-pressure fuel pump failures are common at 60-100k miles causing extended pulse widths and low power under boost.
Related Diagnostic Trouble Codes
P0200P0201P0202P0203P0204
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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