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Code 1 - O2 Sensor

  1. Turn ignition off. Remove BACK-UP light fuse in underhood fuse/relay block for 10 seconds to reset ECU. Start and warm engine to normal operating temperature (cooling fan comes on).
  2. Road test vehicle with transmission in 2nd gear. Accelerate at wide open throttle for at least 5 seconds and then decelerate for at least 5 seconds with throttle completely closed.
  3. If CHECK ENGINE light illuminates and Code 1 is present, perform test for Code 43. If CHECK ENGINE light does not illuminate and Code 1 is not present, problem is intermittent. Check for poor connections and loose wires at connector No. C210 (at right shock tower), and check O2 sensor connector.
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