P0356

P0356 is the cylinder 6 ignition coil primary/secondary circuit fault — V6, V8, V10, or inline-6 engine. Cylinder 6 location: on a V6 (Toyota 2GR, Nissan VQ35, GM 3.6, Ford Cyclone 3.5/3.7) it's the rear-bank rear cylinder (firewall side, hardest to reach), on Ford Modular V8 it's bank 2 second from front, on GM LS V8 it's bank 2 middle-front, on Chrysler Hemi it's bank 2 second position, on BMW/Mercedes inline-6 it's the firewall-end cylinder. Cheapest-first diagnostic: swap the cylinder 6 coil with cylinder 2's (V8) or cylinder 1's (V6 — pull a front-bank coil that's easy to reach), clear codes, drive cycle. Code moves with coil = $35-$120 fix. Code stays at cylinder 6 = the standard trigger-wire/power/ground diagnosis. On rear-bank rear-cylinder V6 positions, this is the heat-soak grave — engine bay temps under load can hit 220-260F on the firewall side, and coils degrade fastest here. Don't condemn the ECM until you've swapped a known-good coil in and confirmed clean trigger wire + clean power + clean ground; rear-bank harness wear on V6s commonly chafes against the firewall or transmission bellhousing.

Vehicle-specific patterns: 2007-2014 Nissan Altima/Maxima/Murano 3.5L VQ35DE cylinder 6 P0356 is the textbook VQ35 case — rear bank rear cylinder, valve cover gasket oil leak is the standard root cause, and replacing the coil without also replacing the rear valve cover gasket guarantees a return visit. 2007-2017 Toyota Camry/Avalon/Highlander 3.5L 2GR-FE cylinder 6 P0356 from Denso COP failure under the intake plenum — plenum removal required, budget for plenum gasket. 2007-2013 BMW N52/N54 cylinder 6 P0356 from Eldor coil batch failure — replace all six on this engine because the rest are days behind. 2011-2019 Ford F-150 3.5L EcoBoost cylinder 6 P0356 from carbon-fouled plug + heat-soaked coil; carbon walnut-blast service ($300-$500) every 60-80K miles prevents recurrence. 2005-2013 GM 5.3L LS truck cylinder 6 P0356 from D585 failure. 2003-2010 Hemi 5.7L cylinder 6 (passenger bank middle) P0356 from boot crack under exhaust heat. Estimated repair: $35 (one coil) to $850 (full coil set + plenum gasket + valve cover gaskets on VQ35).