If any of the following dtcs are set, the ecm enters fail-safe mode to allow the vehicle to be driven temporarily.

Hint:
*: The vehicle can be driven slowly when the accelerator pedal is depressed firmly and slowly. If the accelerator pedal is depressed quickly, the vehicle may speed up and slow down erratically.
Check mode procedureDriver side - side airbag sensor circuit malfunction
Description
The side airbag sensor lh consists of part including the diagnostic circuit
and the lateral deceleration
sensor.
When the center airbag sensor receives signals from the lateral deceleration
sensor, it determines
whether or not the srs should be activated.
Dtc b1620/21 is ...
Removal
Disconnect cable from negative battery
terminal
Caution:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery terminal to
prevent airbag and seat belt pretensioner activation.
Remove radiator support opening cover
Remove front wheel rh
Remove no. 1 ...
Installation
Install water pump assembly
Remove any old seal packing material from the
contact surface.
Apply a continuous line of seal packing as shown in
the illustration.
Seal packing:
toyota genuine seal parking black, three
bond 1207b or equivalent
Standard seal diameter:
2.2 To 2. ...