P0355

P0355 is the cylinder 5 ignition coil primary/secondary circuit fault — this puts you on a V6, V8, V10, or inline-5/inline-6 engine. Cylinder 5 location: on Ford Modular V8 it's the front cylinder of bank 2 (driver side), on GM LS V8 it's the front of bank 2 (passenger side), on Chrysler Hemi it's bank 2 front (passenger side), on most V6s (Toyota 2GR, Nissan VQ35, GM 3.6) it's the rear-bank front cylinder, on BMW inline-6 it's the second from the rear, on Audi/VW inline-5 it's the flywheel-end cylinder. Cheapest-first diagnostic: swap the cylinder 5 coil with cylinder 1's (or a known-good cylinder on the same engine — same coil part number required), clear codes, drive cycle. Code follows the coil = $35-$120 coil replacement. Code stays at cylinder 5 = trigger-wire diagnosis: resistance check ECM-to-coil under 0.5 ohms, B+ feed 12.0-12.6V static / 13.5-14.5V running, ground drop under 0.1V. Scope the ECM trigger pulse for clean square-wave (0-5V or 0-12V, 3-6ms dwell at idle). On bank-2 cylinders, also inspect the coil-bank harness for chafing where it crosses the intake or routes along the firewall — chafe-throughs to the engine block are a documented failure on Ford 5.4L and Nissan VQ35 platforms.

Vehicle-specific patterns: 2004-2010 Ford 5.4L 3V cylinder 5 P0355 (driver-side front) — same TSB 08-7-6 fix, but on the driver bank you also need to check the bank-2 harness routing under the cowl drain for water intrusion. 2005-2013 GM 5.3L LS truck cylinder 5 (passenger bank front) P0355 from D585 failure. 2007-2014 Nissan VQ35 cylinder 5 (rear bank front under intake plenum) P0355 — this is the hardest VQ35 coil to reach and the most commonly oil-soaked from valve cover gasket leak; budget for plenum gasket as part of the repair. 2007-2013 BMW N52/N54 cylinder 5 P0355 from Eldor coil batch failure plus harness chafing on the back of the head. 2005-2014 Toyota Tundra/Sequoia 5.7L 3UR-FE cylinder 5 (driver bank front) P0355 — Denso COP, OE replacement only. 2007-2014 Mercedes M272 V6 cylinder 5 P0355 — known issue with balance shaft gear wear causing timing variance that triggers coil-circuit codes alongside misfire codes; if you see P0355 with P0016 or P0017, suspect the balance shaft. Estimated repair: $35 (one coil) to $5,200+ (M272 balance shaft repair).