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Diagnostic Aids

Normal O2 sensor voltage is .1-.9 volt (varying) in closed loop operation. An open in O2 sensor signal circuit or ground will cause Code 13 to set. If Code 13 is intermittent, refer to TESTS W/O CODES article in this section. Before replacing an ECM, ensure ECM connector is not damaged.

Fig 1: Code 13 Schematic, Oxygen Sensor Circuit Open Circuit

Fig 2: Code 13 Flow Chart, Oxygen Sensor Circuit Open Circuit