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Starting with the codes:
P1131 = Lack Of HO2S Switch - Sensor Indicates Lean
P1143 = Air Assist Control Valve Range/Performance
The first code indicates a problem with the O2 sensor (upstream, or the one before the catalytic converter) and the second code indicates a problem with the idle air control valve.
If the idle air control valve (IAC) is hanging open, the first code could be a symptom of that. Also, if the catalytic converter or the muffler is blocking the flow of exhaust it would cause a similar condition (since the IAC wouldn't be able to compensate). If the exhaust is being blocked, it would make more sense for it to be caused by the muffler, since a blockage across the catalytic converter would show a code for the upstream and downstream O2 sensor as well as the "Check Engine" light flashing while the engine ran.
It is very typical for an IAC valve to seize and also reasonably common for an O2 sensor to fail. You'd be doing yourself a favor if you test the EGR valve as well and make sure you don't have an exhaust system issue.
Hope that helps! |
RV and bus conversion info since 1996.
email Phil Feinstein
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