P0521 — OBD-II trouble code

A generic powertrain OBD-II trouble code. Below are the vehicles and failure patterns where owners report it, drawn from NHTSA complaints.

In ProblemsByVin's analysis of the NHTSA owner-complaint record, owners cite P0521 across 8 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 P0521 8 patterns

2024 Chevrolet Trax

electrical — Engine Oil Pressure Faults and Hesitation

2021 Ford F-150

engine — Excessive oil consumption

2018 Mercedes-Benz GLC-Class

electrical — Crankcase vent system malfunction (P0521)

2016 Chevrolet Equinox

engine — PCV valve freeze-up and rear main seal blow-out (cold-weather defect)

2014 Chevrolet Silverado

engine — Vacuum pump failure and metal debris in oil system

2012 Hyundai Tucson

engine — Engine oil pan leak with insufficient oil supply to bearings

2011 Chevrolet Silverado

engine — Oil pressure sensor and related sensor faults

2009 Chevrolet Silverado

engine — Excessive oil consumption

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 →