DTC P0130/P0131/P0132/P0137/P0138 Front & Rear O2S Sensor CKT

P0130 - Front O2S Sensor Circuit Malfunction
P0131 - Front O2S Sensor Circuit Low Voltage
P0132 - Front O2S Sensor Circuit High Voltage
P0137 - Rear O2S Sensor Circuit Low Voltage
P0138 - Rear O2S Sensor Circuit High Voltage

Install scan tool. Start engine and check if DTC P0130, P0131, P0132, P0137 or P0138 is present. If DTC is present, go to next step. If DTC is not present, problem is intermittent.
Turn ignition off. Disconnect affected O2S harness connector. Turn ignition on. Using DVOM, check voltage between affected O2S harness connector terminal No. 4 and ground. If battery voltage is present, go to next step. If battery is not present, check circuit between terminal No. 4 and fuel pump relay. See appropriate wiring diagram in WIRING DIAGRAMS section.
Turn ignition off. Check for continuity between ECM harness connector terminal No. 12 (front O2S) or terminal No. 39 (rear O2S) and O2S harness connector terminal No. 1. If continuity is not present, check circuit between O2S and ECM. Repair circuit as necessary. If circuit is okay, go to next step.
Reconnect ECM harness connector. Check continuity between O2S harness connector terminal No. 2 and ground. Continuity should be present. If continuity is present, go to next step. If continuity is not present, check circuit between terminal No. 2 and ECM. Repair as necessary.
Reconnect O2S harness connectors. Using scan tool, check O2S output voltage. Output voltage should be 200 millivolts or less with engine decelerating from 4000 RPM and 600-1000 millivolts when engine is raced. With engine at idle, output voltage should fluctuate between 200-1000 millivolts. Also, check O2S heater resistance. With engine off, resistance should be 1.7-2.5 ohms. Replace O2S if output voltage or resistance is not as specified. If output voltage and resistance are okay, go to next step.
Clear DTC. See CLEARING DTC(S) . Retest system. If DTC resets, replace ECM.