Global OBD II Diagnostics
4 – 6• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
44

O2 MONITOR TEST

✓
The O2 Monitor Test is NOT AN ON-DEMAND TEST.
O2 sensors are
NOT tested when selected via the menu. The O2 sensors are t ested when
engine operating conditions are within specified limits.
OBD II regulations require that applicable vehicles monitor and test the
oxygen(O2) sensors to determine problems related to fuel and emissions. The
O2 Monitor Test
allows retrieval of completed O2 se nsors mon itor t est resul ts.
O2 sensors are located before (upstream) and after (downstream) the cata-
lyst(s). The sensors are named (xy) for their position relative to both the cyli nder
banks and the catalysts.
• The O2 sensor for cylinder bank 1 has the prefix
1
y while the O2 sensor for
cylinder bank 2 has the prefix
2
y.
• The O2 sensor upstream of the catalyst (closest to the engine) has the suffix
x
1
while the O2 sensor downstream of the catalyst has suffix x
2
. If the vehi-
cle contains more catalysts, the O2 sensor downstream of the second cat-
alyst has the suffix x
3
and the O2 sensor downstream of the next catalyst
has the suffix x
4
.
• For example,
O2S 21
is the upstream O2 sensor for cylinder bank 2.
The following O2 sensor tests are available:
1) Rich to Lean sensor threshold voltage
2) Lean to Rich sensor threshold voltage
3) Low sensor voltage for switch time
4) High sensor voltage for switch time
5) Rich to Lean sensor switch time
6) Lean to Rich sensor switch time
7) Minimum sensor voltage test cycle
8) Maximum sensor voltage test cycle
9) Time between sensor transitions
10) Sensor Period
Select
O2 Monitor Test
from the
OBDII
Function List
and press .
Select the desired test from the menu
and press . Grouping O2 sen-
sor tests together makes the data eas-
ier to compare.
✓The O2 sensors located upstream (before the catalyst) may perform dif-
ferently than the ones located downstream (after the catalyst) .
Oxygen sensor tests not supported by
the vehicle display three dashes as the
value.
Press the key to return to the O2
Sensor Tests menu or press to
return to the
OBDII Function List.