A fault code doesn’t yet mean the unit or sensor itself is faulty: often it’s the plug and connector leading to it.
Possible causes
- The ECU’s constant power fuse (usually EFI)
- The ECU’s constant power wire: an open circuit or corrosion
- The battery was disconnected or deeply discharged
What you can do yourself
- The code often appears after the battery was disconnected — clear it and see whether it comes back.
- Check the EFI fuse in the under-hood box and the battery terminals.
OOleg’s tip: check the connector
Often the cause is simple — there is no contact in the connector (plug). Look at the connector from the back: remove the rubber seal and you will see whether a wire is corroded or has come off completely. Corrosion shows up as green deposits. Ideally, gently pull each wire towards you one at a time: a sound wire stays in place, while a corroded one simply comes off — it needs to be repaired.
Unplug and inspect connectors with the ignition off.
This is the Toyota and Lexus meaning. On other makes this number means something else: if your car isn’t a Toyota or Lexus, change the make at the top.
Source: Toyota repair manuals: Corolla 2003 RM940U, 4Runner 1996–2002; obdadvisor.com
The explanation comes from the error code reference in the AvtoElektrik PRO app.