Emmissions Prob

[JBeasockjr]

I have a 2002 ford explorer that I have recently had the converters replaced(all 4 of them) because two of them broke down and clogged the other 2. I now have the CEL on and cant seem to narrow things down. Had the codes read displayed P0135 an P1131. After bringing to a mech. Said it could be the EGR valve or IAC. But couldn't narrow things down. Any Help would be appreciated.

[way2old]

Here is some information------I do not see where your mechanic could glean any information about the IAC valve. It indicates either O2 heater circuits or a wiring problem to the O2 sensors. The farther down the list of causes you go, the more unlikely the cause will be.

P0135 - HO2S Sensor Circuit Malfunction (HO2S-11) During testing the HO2S Heaters are checked for opens/shorts and excessive current draw. The test fails when current draw exceeds a calibrated limit and/or an open or short is detected. Short to VPWR in harness or HO2S. Possible causes below.

Water in harness connector.
Open VPWR circuit.
Open GND circuit.
Low battery voltage.
Corrosion or poor mating terminals and wiring
Damaged HO2S heater.
Damaged PCM.
Wiring.
Damaged HO2S heater.
Damaged PCM.

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. Possible causes below.

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)

[JBeasockjr]

I guess alot to check....Where to start O2 sensor and work from there?

[way2old]

Check to be sure all the wiring is good first. If the voltage can't get to sensor and signal can't get back to the PCM------