Spectrum 3.0L GM, Parts & Service Manual

Page: 167 / 327

167
DTC 522635 Oxygen Sensor Failure to Switch Lean, Bank 1
Step Action Value(s) Yes No
1
Did you perform the On-board diagnostics (OBD)
system check?
Go to Step
(2)
Go to On-
Board
Diagnostics
System
Check/
Malfunction
indicator
lamp.
2

With the engine at operating temperature,
monitor the O2 sensor voltage and the short
term fuel trim
Is the O2 sensor switching from rich to lean, and
is the short term correction less than 25%?
No problems
at this time.
Intermittent
problem. Go
to Preliminary
and Intermit-
tent Checks
Go to Step
(3)
3

Check all problems listed in the diagnostic
aids.

For the O2 sensor, also refer to DTC 522635
diagnostics.

For MAP diagnostics, refer to DTC 106

For ECT diagnostics, refer to DTC 110

Verify proper maintenance and condition of
the ignition system.

Verify engine condition with a compression
test.
Were any faults found?
Repair as re-
quired. Go to
step last
Go to Step
(4)
4

Monitor connected with the engine running,
monitor the engine RPM.

One at a time, disconnect each injector and
observe the drop in engine speed.

Do one or more injectors not drop the engine
speed when disconnected?
NOTE: the engine speed will only drop momen-
tarily as the ECU corrects the engine speed.
Go to Step
(6)
Go to Step
(5)
5

Check the fuel pressure.

Is the pressure 88 kPa (12.8 PSI) above at-
mospheric pressure, engine off ±15 kPa (2.2
PSI) and holding steady?
Go to Step
(6)
Replace the
Regulator, Go
to Step (8).
6

Checking injectors

One at time, connect a noid light across
each injector connector.

With the engine running, does the noid light
flash at the connector of the failed injector
connector?
Replace faul-
ty injector Go
to Step (8)
Repair circuit
to the injec-
tor. Go to
step last