DTC P0134: 1/1 O2 Sensor Stays At Center

NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS article.

NOTE: 1/1 O2 sensor is referred to as upstream oxygen sensor in this test. Upstream oxygen sensor operation is monitored when engine is running for more than 2 minutes and engine coolant temperature is more than 170°F (76.7°C). DTC may be stored in Powertrain Control Module (PCM) if upstream oxygen sensor signal voltage is .35-.55 volt for 1.5 minutes. Possible causes are: defective upstream oxygen sensor, defective PCM, or defective connectors or wiring.

Start engine and warm engine to normal operating temperature. With scan tool in ACTUATOR TESTS mode, set engine speed at 1500 RPM. With scan tool in SENSOR mode, read upstream oxygen sensor state. If upstream oxygen sensor state switches, go to next step. If upstream oxygen sensor state does not switch, go to step 4 .
With engine at 1500 RPM, wiggle wiring harness and connectors at upstream oxygen sensor while monitoring upstream oxygen sensor state on scan tool. Upstream oxygen sensor is mounted on exhaust manifold. If upstream oxygen sensor state does not become locked at center while wiggling wiring harness and connectors, go to next step. If upstream oxygen sensor state becomes locked at center while wiggling wiring harness and connector, repair open on wiring harness or connectors between upstream oxygen sensor and PCM as necessary. PCM is located between driver's side front fender and power distribution center, near battery. Perform TEST VER-5A .
Turn ignition off. Check for defective wiring or connections at upstream oxygen sensor and PCM. PCM is located between driver's side front fender and power distribution center, near battery. If no defective wiring or connections exist, test is complete. If defective wiring or connections exist, repair as necessary. Perform TEST VER-5A .
Turn ignition off. Disconnect upstream oxygen sensor connector. Upstream oxygen sensor is mounted on exhaust manifold. Using ohmmeter, check resistance between engine ground and terminal No. 3 (Black/Light Blue wire on 3.0L early build, or Black/Orange wire on 2.4L, 3.0L late build, 3.3L and 3.8L) on wiring harness side of upstream oxygen sensor connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open ground circuit on Black/Light Blue wire on 3.0L early build, or Black/Orange wire on 2.4L, 3.0L late build, 3.3L and 3.8L between upstream oxygen sensor and PCM. PCM is located between driver's side front fender and power distribution center, near battery. Perform TEST VER-5A .
Connect jumper wire between terminal No. 4 (Black/Dark Green wire) on wiring harness side of upstream oxygen sensor connector and positive battery terminal. Turn ignition on with engine off. Using scan tool, read upstream oxygen sensor voltage. If upstream oxygen sensor voltage is one volt or less, go to next step. If upstream oxygen sensor voltage is more than one volt, replace upstream oxygen sensor. Perform TEST VER-5A .
Turn ignition off. Disconnect jumper wire from wiring harness side of upstream oxygen sensor connector and positive battery terminal. Disconnect PCM connectors. PCM is located between driver's side front fender and power distribution center, near battery.
Using ohmmeter, check resistance between terminal No. 4 (Black/Dark Green wire) on wiring harness side of upstream oxygen sensor connector and terminal No. 30 (Black/Dark Green wire) on Black PCM connector C1. If resistance is less than 5 ohms, replace PCM. Perform TEST VER-5A . If resistance is 5 ohms or more, repair open on Black/Dark Green wire between PCM and upstream oxygen sensor connector. Perform TEST VER-5A .