P0269

P0269 means the ECM detected cylinder 3 contribution/balance fault — identical diagnostic logic to P0263/P0266 but for cylinder 3. The ECM monitors crankshaft acceleration per cylinder firing and per-cylinder injector balance rate (typically expressed as mm^3/stroke deviation from the bank nominal), and sets the code when cylinder 3's contribution falls outside roughly +/-8 to 15% of bank average or its balance rate exceeds 2-5 mm^3/stroke deviation. The shop-floor diagnostic flow on cylinder 3 is identical to any cylinder-balance code: (1) live-data the per-cylinder balance rates and identify the magnitude and sign of the deviation. (2) Swap the cylinder 3 injector connector with an adjacent same-bank cylinder, clear, and confirm whether the fault follows the electrical path — this distinguishes injector/wiring from mechanical compression. (3) Return-flow test all injectors with calibrated bottles to confirm whether cylinder 3's injector is over-returning (stuck/dribbling) or normal. (4) Relative compression test via scan-tool starter-current monitoring — looking for less than 15% deviation between cylinders, with anything beyond pointing at compression. (5) Confirm injector trim/IQA codes in the ECM match the etched codes on the actual injectors — this catches the 'someone replaced an injector but didn't recode it' fault that throws balance codes immediately. Critical caveat on cylinder identification: on an inline-6 (Cummins, BMW, Mercedes OM613/648) cylinder 3 is the middle cylinder and historically the one with the most thermal stress; on a V8 the bank assignment for cylinder 3 varies sharply — Ford modular 5.4L vs. GM LS vs. Chrysler Hemi all assign cylinder 3 differently — pull the FSM diagram. Expensive-misdiagnosis caveat: a single cylinder-balance code on a high-mileage diesel is almost always the first of many — replacing only the cylinder 3 injector is rarely the right financial call once you've already broken into the fuel system.

Vehicle-specific patterns: 2001-2004 GM Duramax LB7 throws P0269 as part of the well-documented full-set injector failure pattern — under-the-valve-cover injectors fail together. 2003-2007 Ford 6.0L Powerstroke throws P0269 from HEUI stiction or low HPOP output; if all 8 cylinders show balance codes simultaneously it's typically a hydraulic problem (HPOP, IPR, branch tube leak) not an injector problem. 2008-2010 Ford 6.4L Powerstroke throws P0269 from piezo injector wear or from a failed injection control pressure (ICP) sensor mimicking injector starvation. 2011-2016 Ford 6.7L Powerstroke throws P0269 after CP4 contamination events. 2003-2018 RAM Cummins 5.9L/6.7L throws P0269 from Bosch CR injector wear — the middle cylinder on the inline-6 commonly shows balance drift first. 2007-2018 Mercedes Sprinter OM642 throws P0269 from piezo injector wear; trim-code matching after replacement is critical. 2009-2014 Audi/VW TDI 2.0L CR (CBEA/CJAA) throws P0269 from injector nozzle wear and post-CP4-grenade contamination. Estimated repair: $400 to $7,500.