E4: Check For O2 Sensor Failure

With the conditions held as E3, suddenly decelerate to idle.

- Has the voltage dropped to 400mV or less?
Yes
GO to E5 E5: Check For O2 Sensor Failure
No
Renew O2 sensor Reconnect plug(s)
GO to E7 E7: Heated O2 Sensor Short Circuit to Ground