P1603 — manufacturer-specific powertrain code

P1603 is a manufacturer-specific powertrain code: it is defined by the carmaker, not by the OBD-II standard, so the same code can mean different things on different brands. Below are the vehicles and failure patterns where owners report it, drawn from NHTSA complaints — the most reliable guide to what it means in practice.

Ask A Mechanic

In our record, P1603 is reported most often on Toyota, Subaru and Jeep vehicles , against powertrain and engine failure patterns , across 2006–2018 model years. Toyota alone accounts for 67% of them.

In ProblemsByVin's analysis of the NHTSA owner-complaint record, owners cite P1603 across 6 vehicle failure patterns. Diagnostic codes in complaints are reported by owners and are unverified — they point to where this code shows up, not a confirmed diagnosis. Open a page below for the full pattern (symptoms, mileage, repair costs owners cite).

Vehicles where owners report P1603 6 patterns

2018 Subaru Crosstrek

engine — Acceleration problems and jerky/knocking noise after ECM service

2018 Toyota RAV4

powertrain — Stalling in Moving Traffic / Loss of Power and Difficulty Restarting

2015 Toyota Highlander

electrical — Engine Stall and Loss of Power

2013 Toyota Sienna

body — Power sliding door failure to open/close/latch

2011 Toyota Highlander

powertrain — Oil Cooler Pipe Rupture & Catastrophic Engine Damage

2006 Jeep Grand Cherokee

powertrain — Transmission Control Module (TCM) / Powertrain Control Module (PCM) Electrical Failure

Codes are pulled from what owners wrote in their NHTSA filings — they're allegations, not a shop diagnosis. Always confirm with a live scan. Browse all diagnostic codes →