Toyota Corolla 2003–2004 — technical service bulletin
Bulletin 02804 · NHTSA communication 10010314 · issued Jul 19, 2004
Technical service bulletin
communication type
Engine and Engine Cooling
component
2003–2004
model years
2
vehicle entries
Official summary
Malfunction indicator lamp on with diagnostic trouble code p0420. *tt update. *tt
Vehicles covered
What a TSB means. Technical service bulletins are repair guidance manufacturers send to dealers — they are not recalls, and repairs are not automatically free (warranty extensions are an exception worth checking). The full document is available via NHTSA’s vehicle lookup.