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• Find the Cause

Trouble code P1131 means that the powertrain control module has detected a lean condition for engine bank No.1. Code P1131 can be caused by a vacuum leak, fuel injector problem, ignition problem or by a faulty oxygen sensor. You can find the oxygen sensor that reports this condition in the exhaust pipe for engine bank No.1, before the catalytic converter.

Find the Cause

Inspect the engines vacuum lines first. Replace any vacuum line the is damaged or leaking. If the vacuum lines are in good condition, move on to the ignition system. Check the spark plugs, spark plug wires, distributor cap and distributor rotor, if so equipped. If the ignition system looks good, have the fuel system and oxygen sensor checked.