P0303 on Toyota vehicles Cylinder 3 is misfiring

A model year is listed because the code is named in its own record — a bulletin filed against it, or an owner’s complaint about it — not because every one of these vehicles sets it. Counts are documents in NHTSA’s files, not failure rates.

Bulletins and campaigns Toyota filed with NHTSA whose summary names P0303. Quote the document number at the service desk — it is a diagnosis the maker has already written down.

• T-SB-0116-15 REV Service bulletin
  2016-08-11 · Hybrid Propulsion System
• TSB: REVISION NOTICE AUGUST 11, 2016 REV1: APPLICABILITY HAS BEEN UPDATED TO INCLUDE 2016 MODEL YEAR PRIUS V VEHICLES. ANY PREVIOUS PRINTED VERSIONS OF THIS BULLETIN SHOULD BE DISCARDED. SOME 2010 – 2015 MODEL YEAR PRIUS (2ZR-FXE EQUIPPED) VEHICLES, 2012 – 2015 MODEL YEAR PRIUS PHV VEHICLES, AND 2012 – 2016 PRIUS V (2ZR-FXE EQUIPPED) VEHICLES MAY EXHIBIT A “RUNS ROUGH” AND/OR MIL “ON” CONDITIO
• T-SB-0116-15 Rev Service bulletin
  2016-08-11 · Engine And Engine Cooling — Exhaust System — Emission Control — Gas Recirculation Valve (Egr Valve)
• TSB: REVISION NOTICE August 11, 2016 Rev1: Applicability has been updated to include 2016 model year Prius V vehicles. Any previous printed versions of this bulletin should be discarded. Some 2010 - 2015 model year Prius (2ZR-FXE equipped) vehicles, 2012 - 2015 model year Prius PHV vehicles, and 2012 - 2016 Prius V (2ZR-FXE equipped) vehicles may exhibit a "runs rough" and/or MIL "ON" conditio
• T-SB-0147-16 Service bulletin
  2016-10-14 · Back Over Prevention
• TSB: Some 2013 ? 2015 Prius PHV, Prius and 2013 ? 2016 Prius V vehicles may exhibit a vibration due to rough idle and/or tapping noise from the HV transaxle at cold start. The check engine light may also illuminate with (DTC) P0300, P0301, P0302, P0303, P0304 (Random/Multiple Cylinder Misfire Detected). The Engine Control Module/ECM (SAE Term: Powertrain Control Module/PCM) logic has been modifie
• T-SB-0148-19 Service bulletin
  2019-10-22 · Engine And Engine Cooling
• TSB: Some 2017 ? 2019 model year Highlander HV vehicles may exhibit a MIL ON condition with one or more of the following Diagnostic Trouble Codes (DTCs): ? P0301 ? Cylinder 1 Misfire Detected ? P0302 ? Cylinder 2 Misfire Detected ? P0303 ? Cylinder 3 Misfire Detected ? P0304 ? Cylinder 4 Misfire Detected ? P0305 ? Cylinder 5 Misfire Detected ? P0306 ? Cylinder 6 Misfire Detected Follow the Repair

A stored code names the test that failed, never the part that caused it. The record above is what Toyota and its owners have filed about it; the code’s page across every make has the whole file.