P0171

DTC's P0170, P0171, P0172:

DIAGNOSTIC TROUBLE CODES PO170, PO171, PO172
ADAPTATION FAULTY

Symptoms of fault
The malfunction indicator lamp is on.
Deterioration in drivability, unsteady idling.
Any other diagnostic trouble codes (pressure sensor, oxygen sensor).

Condition
The ECM has increased or decreased the injection times to the maximum without it being possible to achieve lambda = 1.0.

Diagnostic procedure
1. Check other diagnostic trouble codes in Trionic.

- Read out all the diagnostic trouble codes with the ISAT scan tool.
- If P0105, P0106, P0107, P0108 appears on the display, manifold absolute pressure sensor, start fault diagnosis there.
- If P0130, P0131, P0132 appears on the display, oxygen sensor, start fault diagnosis there.

2. 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.

DTC's P0170, P0171, P0172:

3. Check the operation of the pressure sensor using a pressure gauge and a pressure/vacuum pump.

- Ignition switched ON.
- Generate a positive pressure of 0.6 bar and a negative pressure of -0.6 bar.

With the ISAT scan tool connected and in the "READ FUNCTIONS" menu and the "INTAKE PRESSURE" command, the ISAT scan tool must show 160 ± 5 kPa and 4O ± 5 kPa respectively (the ISAT may show slightly lower values when measuring at high altitude).

The measurement is intended to detect any shift in the operating range of the pressure sensor.

4. Then check:

- That the fuel pressure is correct.
- That no air leakage occurs in the exhaust system ahead of the oxygen sensor or at its mount.

5. Erase the diagnostic trouble code and drive the car to see whether the DTC is generated again.

- If the diagnostic trouble code is registered, continue at "Procedure before replacing ECM".
- If the diagnostic trouble code is not registered, the action taken is correct. Otherwise the fault is intermittent in nature.