2003 Toyota Sienna Q&A
2003 Toyota Sienna Question: oxygen heater circut malfunction
P0135 indicates a fault in the cylinder bank #1, O2 sensor #1 heater circuit. Check for 12 volts and ground when the engine's running cold. the heater won't be on all the time so you need to see it on sometimes. If not, look for a fault in the wiring or the connector at Bank 1 Senosr 1 circuiut. - Superbob
code is po135 oxygen heater circut malfunction. I replaced both front and rear oxygen sensors but that did not help. someone said they though...