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Test TC-194A: 1/2 O2 Sensor Slow During Catalyst Monitor

NOTE: This test does not apply to AB, TJ, XJ or ZJ bodies. For connector terminal identification, see CONNECTOR IDENTIFICATION . For component location and wiring diagram, see WIRING DIAGRAMS article.
CAUTION: Allow Heated Oxygen Sensor (HO2S) to cool to room temperature before checking resistance.
NOTE: On AN body (2WD) equipped with 5.9L engine and BE/BR bodies with 8.0L medium-duty engine, 1/2 Heated Oxygen Sensor (HO2S) is located in pre-catalyst position. On all other bodies, 1/2 HO2S is located in downstream position. On models equipped with 4 HO2S, 1/2 HO2S is located in left downstream position.
  1. 1/2 O2 SENSOR SLOW DURING CATALYST MONITOR DTC sets if 1/2 Heated Oxygen Sensor (HO2S) voltage is switches from less than 0.39 volt to more than 0.60 volt fewer times than required. Possible causes are: exhaust leak, fuel contamination, HO2S heater failure, defective HO2S, defective wiring or connectors, or engine mechanical problems. Go to next step.
  2. Start engine. Check exhaust system for leaks between engine and catalytic converter. Repair exhaust system as necessary and perform TEST VER-2A: ROAD TEST VERIFICATION . If exhaust system is okay, go to next step.
  3. Check exhaust for excessive smoke caused by oil or coolant consumption. Repair engine mechanical condition as necessary, replace catalytic converter and HO2Ss, and perform TEST VER-2A: ROAD TEST VERIFICATION . If engine mechanical condition is okay, go to next step.
  4. Turn ignition off. Disconnect 1/2 HO2S connector. Inspect connector and terminals for damage. Repair connector and terminals as necessary and perform TEST VER-2A: ROAD TEST VERIFICATION . If connector and terminals are okay, go to next step.
  5. Using an external ohmmeter, check resistance between ground and 1/2 HO2S connector, ground circuit (Black/Light Blue wire). If resistance is 5 ohms or more, repair open sensor ground circuit and perform TEST VER-2A: ROAD TEST VERIFICATION . If resistance is less than 5 ohms, go to next step.
  6. Disconnect Powertrain Control Module (PCM) connectors. Inspect connectors and terminals for damage. Repair connectors and terminals as necessary and perform TEST VER-2A: ROAD TEST VERIFICATION . If connectors and terminals are okay, replace 1/2 HO2S and perform TEST VER-2A: ROAD TEST VERIFICATION .
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