P0291 - Cylinder 11 Injector Circuit Low
Last updated:
System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P0291 is set when the Engine Control Module (ECM) detects a lower than expected voltage in the fuel injector control circuit for cylinder number 11. This typically indicates a short circuit to ground or a faulty injector solenoid with low internal resistance. The ECM monitors the voltage drop during the injector's duty cycle; if the voltage remains below a calibrated threshold when the driver is on, the code is triggered.
Possible Causes
Faulty fuel injector (shorted solenoid)
Damaged wiring harness (chaffing or short to ground on signal wire)
Corrosion or poor connection in the injector connector
Internal ECM failure
Symptoms
Recommended Solution
- Visual Inspection: Inspect the wiring harness for cylinder 11 injector for any chafing or heat damage. Check the connector for signs of corrosion or moisture.
- Resistance Test: Unplug the injector and measure the resistance across the terminals using a multimeter. Typically, it should be 10-16 Ohms. A value near 0 Ohms confirms a short.
- Circuit Testing: Verify 12V supply at the connector and use an oscilloscope to check the driver signal and flyback voltage pulses from the ECM.
- Component Replacement: Replace the fuel injector if resistance is out of spec and clear the DTC.
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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