Engine Controls/A/C - Revised DTC Diagnostics
Bulletin No.: 04-06-04-016Date: March 23, 2004
SERVICE MANUAL UPDATE
Subject:
Revised DTC P0135, P0141, P0155, or P0161 Heater Performance and Revised DTC P0140, P0160, P0134, P0154 HO2S Insufficient Activity
Models:
2004 Pontiac GTO
with 5.7L Engine (VIN G - RPO LS1)
This bulletin is being issued to revise DTC P0135, DTC P0141, DTC P0155, or DTC P0161 Heater Performance and Step 2 of DTC P0140, P0160, P0134, P0154 HO2S Insufficient Activity in the Engine Controls sub-section of the Service Manual. Please replace the current information in the Service Manual with the following information.
The following information has been updated within SI. If you are using a paper version of this Service Manual, please make a reference to this bulletin on the affected page.
DTC P0135, P0141, P0155, or P0161 Heater Performance Circuit Description
The heated oxygen sensor (HO2S) must reach operating temperature to provide an accurate voltage signal. A heating element inside the H025 minimizes the time required for the sensor to reach operating temperature. Voltage is provided to the heater by the ignition 1 voltage circuit through a fuse. With the engine running, ground is provided to the heater by the H025 heater low control circuit, through a low side driver within the powertrain control module (PCM). The PCM commands the heater ON or OFF to maintain a specific H025 operating temperature range. The PCM determines the temperature by measuring the current flow through the heater. When the heater is in the ON state, the PCM will pulse the heater OFF for a duration of 50 ms, once per second. When the heater is in the OFF state, the PCM will pulse the heater ON for a duration of 50 ms, once per second. The PCM monitors the heater current with the engine running. The PCM also calculates the heater resistance on a cold start. Both diagnostics will only run once per ignition cycle. If the PCM detects that the heater current or the heater calculated resistance is not within the expected range, the DTCs will set.
DTC Descriptors
This diagnostic procedure supports the following DTCs:
^ DTC P0135 Heater Performance Bank 1 Sensor 1
^ DTC P0141 Heater Performance Bank 1 Sensor 2
^ DTC P0155 Heater Performance Bank 2 Sensor 1
^ DTC P0161 Heater Performance Bank 2 Sensor 2
Conditions for Running the DTC
Heater Current Test
^ DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0200, P0300, P0443, P0496, P1111, P1112, P1114, P1115, P1121, or P1122 are not set.
^ The engine coolant temperature (ECT) is more than 50°C (122°F).
^ The ignition 1 voltage is between 10-18 volts.
^ The engine speed is between 500-3,000 RPM.
^ The engine is running for more than 120 seconds.
^ The mass air flow (MAF) is between 3-40 gls.
^ The scan tool output controls are not active.
^ DTCs P0135, P0141, P0155, and P0161 run twice per ignition cycle when the above conditions are met.
Heater Resistance Test
^ The ignition is OFF for more than 10 hours.
^ The engine coolant temperature is between -30 and +45°C (-22 and +113°F) at engine start-up.
^ The engine coolant temperature minus the intake air temperature is less than 8°C (14°F) at engine start-up
^ The engine is started.
Conditions for Setting the DTC
The PCM detects that the affected HO2S Heater Current is more than 3.125 amps or less than 0.25 amps.
and
The PCM detects that the affected HO2S Heater Resistance is more than 3.125 ohms or less than 9.81 ohms.
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.
Test Description
��k1:
�nl1:
The number below refers to the step number on the diagnostic tables shown.
9. With no fault present, the test lamp will blink once per second.
Disclaimer