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 key doesn’t respond: a damaged chip or someone else’s key
- The antenna coil around the ignition switch or its connector
- The immobilizer ECU or its power supply
What you can do yourself
- Try the spare key: if it starts with it — the problem is the first key; if it doesn't start — the antenna at the ignition switch or the car's control unit.
- Move other keys, tags and metal key fobs away from the key — they interfere with recognition.
- Dim dashboard — check the battery: with low voltage the immobilizer may not recognize the key.
- Car with a Start button: hold the key fob right against the button and press it. On many cars there is an antenna there.
- The immobilizer is never disabled or bypassed: it is theft protection. The fault is found and fixed.
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: obdadvisor.com, Toyota 4Runner 1996–2002 repair manual (ether3al.com)
On Oleg’s website:Car computer diagnostics ↗
The explanation comes from the error code reference in the AvtoElektrik PRO app.