-
Expert
59 Answers
- Posted on Mar 17, 2011
Re: My ford taurus SE 1999 have 3 codes P1504, P1507 and...
DTC
Description
Possible Causes
Diagnostic Aides
P1504 - Idle Air Control (IAC) Circuit
Malfunction
This DTC is set when the PCM detects an electrical
load failure on the IAC output circuit.
- IAC circuit open
- VPWR to IAC solenoid open
- IAC circuit short to PWR
- IAC circuit short to GND
- Damaged IAC valve
- Damaged PCM
- The IAC solenoid resistance is from 6 to 13 ohms.
- IAC valve stuck open
- Vacuum leaks
- Failed EVAP system
- Damaged PCM
- The IAC solenoid resistance is from 6 to 13 ohms.
P1507 - Idle Air Control (IAC) Underspeed Error
This DTC is set when the PCM detects engine idle speed
that is less than the desired rpm.
- IAC circuit open
- IAC circuit short to PWR
- VPWR to IAC solenoid open
- Air inlet is plugged
- Damaged IAC solenoid
- Damaged PCM
- The IAC solenoid resistance is from 6 to 13 ohms
- Disconnect IAC valve and look for no change in engine rpm as an indication
of a stuck or damaged valve
P1131 - Lack of HO2S-11 Switch, Sensor Indicates
Lean
A HEGO sensor indicating lean at the end of a test is
trying to correct for an over-rich condition. The test fails when the fuel
control system no longer detects switching for a calibrated amount of time.
- Electrical:
- Short to VPWR in harness or HO2S
- Water in harness connector
- Open/Shorted HO2S circuit
- Corrosion or poor mating terminals and wiring
- Damaged HO2S
- Damaged PCM
- Fuel System:
- Excessive fuel pressure
- Leaking/contaminated fuel injectors
- Leaking fuel pressure regulator
- Low fuel pressure or running out of fuel
- Vapor recovery system
- Induction System:
- Air leaks after the MAF
- Vacuum Leaks
- PCV system
- Improperly seated engine oil dipstick
- EGR System:
- Leaking gasket
- Stuck EGR valve
- Leaking diaphragm or EVR
- Base Engine:
- Oil overfill
- Cam timing
- Cylinder compression
- Exhaust leaks before or near the HO2S(s)
A fuel control HO2S PID switching across 0.45 volt from 0.2 to 0.9 volt
indicates a normal switching HO2S.
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