P0291
Cylinder 11 Injector Circuit Low
If your code reader dashboard displays the generic DTC error code P0291, your vehicle is currently experiencing an active failure related to "Cylinder 11 Injector Circuit Low". Proper system troubleshooting is required to safely clear this warning.
Driver's Summary
Your vehicle's computer logged P0291 after detecting a malfunction in the cylinder 11 injector circuit low system. In practice, this fault causes engine shaking, lack of power on acceleration. Given the high severity of this code, continuing to drive risks significant mechanical damage. Have it diagnosed immediately.
Symptoms
Engine shaking, lack of power on acceleration
Common Causes
- Defective Cyl 11 fuel injector
- Wiring harness shorted to ground
- Corroded injector plug
- PCM driver failure
How to Fix
- 1 Replace Cyl 11 fuel injector
- 2 Repair wiring harness
- 3 Clean electrical contacts
- 4 Reflash or replace PCM
Technical Explanation
The ECM detects code P0291 by continuously monitoring the relevant sensor circuit against calibrated threshold values stored in its non-volatile memory. The PCM monitors crankshaft rotational velocity via the CKP sensor at a resolution of individual tooth gaps on the reluctor ring. A combustion event in each cylinder produces a measurable acceleration spike; its absence or weakness is flagged as a misfire event within a 200-revolution or 1000-revolution test window. The MIL illuminates after the fault is confirmed on two consecutive drive cycles, and the freeze frame data captured at first detection is stored in the PCM's memory for diagnostic reference.
Is It Safe to Drive?
With P0291 active, your engine or transmission is not operating within design parameters. Short-term driving may seem fine, but internal damage is accumulating — particularly to defective cyl 11 fuel injector.
Mechanic's Pro Tip
Module replacement should always be the last resort for P0291 after exhaustively verifying all power supply circuits, ground connections, and communication bus wiring. Use a wiring diagram to locate all fuses, relays, and ground points for the affected module, and measure voltage drop on each ground with the circuit loaded. A module "failure" is frequently a corroded ground eyelet or a weak battery causing brownout conditions — fix these first and you'll save hundreds of dollars on an unnecessary module replacement.
Related Fault Codes
Frequently Asked Questions
What does OBD2 code P0291 mean?
OBD2 code P0291 refers to Cylinder 11 Injector Circuit Low. If your code reader dashboard displays the generic DTC error code P0291, your vehicle is currently experiencing an active failure related to "Cylinder 11 Injector Circuit Low". Proper system troubleshooting is required to safely clear this warning.
What are the most common symptoms of DTC P0291?
Drivers experiencing code P0291 typically report: Engine shaking, lack of power on acceleration.
Is it safe to drive with trouble code P0291 active?
With P0291 active, your engine or transmission is not operating within design parameters. Short-term driving may seem fine, but internal damage is accumulating — particularly to defective cyl 11 fuel injector.
How much does it cost to fix code P0291?
The estimated repair cost for P0291 ranges from $150 to $500 USD. Injector replacement: 200 - 500
Injector replacement: 200 - 500
Need Professional Diagnostic Assistance?
Always verify sensor signals and wiring integrity with an OBD2 scanner before purchasing replacement parts.
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