P02B1 - Cylinder 6 Injector - Circuit High
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P02B1 is set when the Engine Control Unit (ECU) detects an abnormally high voltage on the fuel injector control circuit for cylinder 6. This typically points to a short to voltage (12V or 24V supply) in the wiring harness or an internal fault in the injector solenoid. The ECU monitors the feedback voltage from the low-side driver; if this voltage remains equal to source voltage during the command phase, the fault is triggered. This will likely cause a misfire and may trigger a limp-home mode to prevent catalytic converter damage.
Possible Causes
Short to voltage in the wiring harness between the ECU and the injector
Faulty fuel injector (internal solenoid short circuit)
Damaged injector connector (moisture or oxidation causing a bridge to power pin)
Internal short circuit in the Engine Control Unit (ECU)
Symptoms
Recommended Solution
- Visual Inspection: Check the wiring and connector for injector 6 for damage, chafing, or corrosion.
- Resistance Measurement: Disconnect the injector and measure resistance across the pins (normally 12–16 Ohms for high-impedance injectors; check OEM specs). 0 Ohms indicates a short.
- Voltage Testing: With the ignition ON, measure voltage on the control wire. It should not show constant battery voltage if the ECU is not commanding it.
- Oscilloscope Analysis: Check the injector signal waveform. You should see a square wave during operation. A flat 12V line indicates a short to voltage.
- Component Replacement: Replace the injector if internally shorted or repair the wiring harness.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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