Question
idle air control valve
iI have discovery V8i 4.0 L 1997 its engine light is on, and the code reader showes following codes.
1. P1193-manufacturer control-Fuel Air Metering
2. P0138-O2 sensor circuit high volts (bank 1 sensor 2)
3. P1448-Manufacturer control-Auxillary emmision control
4. P1193-Manufacturer control-fuel air metering
i have checked the idle air contol valve which is like big nail shape it was covered with black sluge(photo attached). i cleaned it and erased the codes thorough code reader. the vehicle ran good for two days but the engine light came again with the same codes. please help
AnswerCodes P0138 and P1193 are both linked to a down stream (post}cat O/2 sensor heater cuicuit, which can be easily tested for an open circuit with an ohm meter. Two wires on the sensor are the internal heater for the sensor and should have an ohm reading acros them that can be compared with readings from other sensors on the vehicle. An open circuit requires replacement of the sensor.
P1148 indicates an evaporative leak, which will need to be diagnosed with an evaporative leak tester, smoke test or, if you are lucky, by a visual inspection, i.e. missing gas cap, cap seal, or a disconnected hose.
]
