Saab 9000 - Page 141

138 Fault diagnosis
Diagnostic trouble codes -P0170, P0171, P0172 { contd.)
3~
3 Check pressure sensor operation
- Turn the ignitlon switch to the ON position and
then back to the OFF position.
- Connect an ISAT scan tool.
- Select "READ FUNCTIONS".
- Select
"INTAKE PRESSURE".
The ISAT scan tool should show a reading of about
102 kPa (NOTE: the reading is dependent·on air
pressure).
- First build up a pressure of 0.6 bar and. then
create a vacuum of - 0.6 bar. Use a pressure
gauge and a pressure/vacuum pump.
The ISAT scan tool should show readings of 160
±
5 kPa and 40 ± 5 kPa respectively (the ISAT scan
tool readings may be somewhat lower at high alti-
tudes).
The measurement is intended to detect any·shift in
the operating range of the pressure sensor.
Are·the readings OK?
IYES I Continue with point 4.
I NO r Change the pressure sensor and continue
with point 5.
I 4
~===--t.
I~~
0000 I
0000
0000
0000
0 0 c:::J
+0.6 bar
I~~
0000
0000
0000
0000
0 0 c:::J
-0.6 bar
[~~
i
~
. ;:
0000
0000
0000
0000
0 0 c:::J
________ _.5
4 Other checks
Check:
• that the EVAP canister purge valve is closed in the
zero-voltage state
• fuel pressure and flow
• that no air leakage occurs in the exhaust system
· ahead of the front heated oxygen sensor or at its
mounting.
Checks OK?
I YES I Continue with point 5.
I NO I Rectify the fault and proceed to point 5.
Saab9000