P1134

.CIRCUIT DESCRIPTION
This diagnostic applies only to vehicles built with isolated grounded heated oxygen sensors (HO2S). To identify the HO2S, refer to Computers and Controls Systems Component Views.

The powertrain control module (PCM) monitors the HO2S activity. During the monitor period the PCM counts the number of times that the HO2S responds from rich to lean and from lean to rich and adds the amount of time needed to complete all transitions. With this information, an average time for all transitions can be determined. The PCM then divides the rich to lean average by the lean to rich average to obtain a ratio. A DTC sets if the HO2S ratio is not within range.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0131, P0132, P0134, P0135, P0151, P0152, P0154, P0155, P0200, P0300, P0401, P0404, P0405, P0440, P0442, P0446, P0452, P0453, P1120, P1125, P1220, P1221, P1258, P1404, P1441, P1514, P1515, P1516, P1517, or P1518 are not set.
^ The engine coolant temperature (ECT) is more than 65°C (149°F).
^ The engine run time is more than 160 seconds.
^ The evaporative emission (EVAP) purge solenoid command is more than 1 percent.
^ The mass air flow (MAF) is between 23-50 g/s.
^ The engine speed is between 1,200-3,000 RPM.
^ For vehicles without throttle-actuated control (TAC), the throttle position (TP) is more than 5 percent.
^ For vehicles with TAC, the TP indicated angle is 5 percent more than the value observed at idle.
^ The vehicle is operating in Closed Loop.
^ The ignition 1 signal is between 9-18 volts.
^ The fuel tank level remaining is more than 10 percent.
^ Intrusive tests are not in progress.
^ The scan tool output controls are not active.
^ The above conditions are met for 100 seconds.

CONDITIONS FOR SETTING THE DTC
The HO2S transition time ratio is not within a calibrated range.

ACTION TAKEN WHEN THE DTC SETS
^ The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
^ Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS

IMPORTANT: Never solder the HO2S wires. For proper wire and connector repairs, refer to Wiring Repairs or Connector Repairs in Diagnostic Aids.

Inspect for the following conditions:
^ An improperly installed air cleaner outlet duct
^ The air cleaner outlet duct for a collapsed duct, restrictions, or a missing or plugged air filter
^ Throttle body and intake manifold vacuum leaks
^ A damaged or blocked throttle body inlet
^ Exhaust system for corrosion, leaks, or loose or missing hardware. Refer to Exhaust Leakage in Exhaust System.

^ The HO2S is installed securely and the pigtail harness is not contacting the exhaust manifold or wires
^ HO2S contamination
^ The vacuum hoses for splits, kinks, and proper connections
^ Excessive water, alcohol, or other contaminants in the fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (W/O Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (W/ Special Tool) Testing and Inspection

^ PCM sensor grounds that are clean, tight, and properly positioned

An intermittent may be caused by any of the following conditions:
^ A poor connection
^ Rubbed through wire insulation
^ A broken wire inside the insulation Thoroughly inspect any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent and Poor Connections in Diagnostic Aids.

If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Diagnostic Aids.

TEST DESCRIPTION

Steps 1-6:

Steps 7-12:

Steps 13-20:

Steps 21-23:

The numbers below refer to the step numbers on the diagnostic table.
2. After the HO2S heater is commanded ON, the HO2S heater heats up causing the HO2S signal voltage to either increase or decrease. This indicates that the HO2S heater is OK.
3. If the HO2S voltage is varying outside the specified range, the condition is not present.
6. If the test lamp illuminates, the low reference circuit between the HO2S and PCM terminal C1-63 is OK and the PCM low reference terminal is OK.
7. If the voltage is below the specified value, the high signal circuit, the low reference circuit, and the PCM are OK.
11. The opposite bank HO2S must be disconnected to isolate a short to ground in the HO2S heater high control circuit.
15. Resistance within the specified range indicates the HO2S heater is OK.