P0170

DIAGNOSTIC TROUBLE CODES P0170, P0171, P0172
Adaptation Faulty

Fault Symptom.
The CHECK ENGINE lamp (MIL) is on. Poorer engine performance, hunting at idling speed. Any other diagnostic trouble codes (pressure sensor, oxygen sensor).


Conditions.
The control module has increased or decreased injection times by the maximum amount but Lambda = 1.0 cannot be achieved.





DIAGNOSTIC PROCEDURE

1. Checking Of Other Diagnostic Trouble Codes In The Trionic System.
Use the Scan Tool to obtain readouts of all the diagnostic trouble codes.

If the Scan Tool shows P0105, P0106, P0107, P0108, manifold absolute pressure sensor, begin fault diagnosis there.

If the Scan Tool shows P0130, P0131, P0132, oxygen sensor, begin fault diagnosis there.

2. Checking For Air Leakage
Check that no air leakage occurs at the following places:
- the hose between the pressure sensor and the intake manifold,
- the hose between the fuel pressure regulator and the intake manifold.






3. Checking The Operation Of The Pressure Sensor
Turn the ignition switch to the ON position and then back to the OFF position.
Connect the Scan Tool,
Select "READ FUNCTIONS".
Select "INTAKE PRESSURE".

The Scan Tool should show a reading of about 102 kPa (NOTE: the reading is dependent on barometric pressure).

First build up a positive pressure of 0.6 bar and then a negative pressure of -0.6 bar. Use a pressure gauge and a pressure/vacuum pump.

The Scan Tool should show readings of 160 ±15 kPa and 40 ±5 kPa (slightly lower readings might be obtained at high altitudes).

The readings are designed to reveal any shift in the operating range of the pressure sensor.

If the readings are OK, continue with point 4.

If the readings are not OK, change the pressure sensor.

4. Other Checks
Check that:
- the EVAP canister purge valve closes when energized (it is normally open when no current is applied to it).
- the fuel pressure is correct
- air leakage does not occur in the exhaust system ahead of the oxygen sensor or at its mounting points.
- the secondary air injection control valve is fully closed (cars with a secondary air injection system).

5 . Final Check
Clear the diagnostic trouble code, drive the car on test and check whether the trouble code is generated afresh.

If the DTC is generated again, refer to Before Replacing A Control Module.

If the DTC is not generated again, the action taken to rectify the fault was correct, otherwise the fault is of intermittent nature.