P0050

P0050 is the Bank 2 mirror of P0030 — the heater control circuit for the upstream O2 sensor on the bank that does NOT contain cylinder #1. Only V-configuration engines (V6, V8, V10) and some opposed engines have a Bank 2. The diagnostic path is identical to P0030 but on the opposite side of the engine. Cheapest-first: ohm the upstream Bank 2 sensor cold at the connector — 2-10 ohms narrowband, 1-3 ohms wideband. Verify the heater fuse (often shared with Bank 1, so a blown fuse usually sets P0030+P0050 together — if you only see P0050, the fuse is good). Key-on, confirm 12V at the supply pin, then scope the ground-side PWM during the first 60 seconds. Heater current 0.5-2A peak, closed-loop entry inside 30-90 seconds. Pay attention to whether the code sets alone or with its Bank 1 twin — paired codes point to a shared fuse, ground, or PCM power feed; isolated codes point to the specific bank's harness or sensor. Expensive misdiagnosis: replacing both upstream sensors when only Bank 2 is faulty — confirm by swapping the suspect sensor to the opposite bank and seeing if the code follows.

Vehicle-specific patterns: GM 5.3L/6.0L/6.2L LS trucks and SUVs (Silverado/Tahoe/Yukon/Escalade 2007-2014) chronically melt the Bank 2 upstream harness onto the passenger-side manifold heat shield — same TSB family as P0030 but mirrored. Ford 5.4L 3V (F-150/Expedition 2004-2010) Bank 2 upstream connector corrodes from cowl-drain runoff on the passenger side. Toyota 2GR-FE (Camry V6/Sienna/Avalon 2007-2014) Bank 2 wideband AFR sensors fail with age similar to Bank 1, Denso 234-9052 for the rear bank. Chrysler 5.7L HEMI (Ram 1500/300/Charger 2005-2014) Bank 2 upstream wiring chafes at the engine-to-firewall bracket. Estimated repair: $120 to $450.