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2003 Escalade CEL code p0135 (HO2S Heater Performance Bank 1 Sensor 1)

17K views 4 replies 4 participants last post by  the cadillac man 
#1 ·
I've got a P0135 CEL code. Reset it & it comes back typically with this same code duplicated within a couple of days. Before I go & replace the 02 sensor are there any other checks to make before replacing it, where exactly is the bank 1 sensor 1 located, & a part number would be appreciated? I usually buy my parts off ebay. Thanks.
 
#2 ·
CutNpaste info from the service manual:

DTC P0135 or P0155 W/5.3L or 6.0L

Circuit Description

The heated oxygen sensor (HO2S) must reach operating temperature to provide an accurate voltage signal. A heating element inside the HO2S 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 HO2S 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 HO2S 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 also monitors the current flow through the heater for diagnosis. This diagnostic will only run once per ignition cycle. If the PCM detects that the current is above or below a specified range, DTC P0135 or P0155 sets.

Conditions for Running the DTC

-DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0169, P0178, P0179, P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1514, P1515, P1516, P1518, P2108, P2135 are not set.
-The ECT Sensor parameter is more than 50°C (122°F).
-The Fuel Alcohol content parameter is less than 90 percent.
-The Ignition 1 Signal parameter is between 10-18 volts.
-The MAF Sensor parameter is between 3-40 g/s.
-The Engine Speed parameter is between 500-3,000 RPM.
-The Engine Run Time parameter is more than 120 seconds.

Conditions for Setting the DTC

-The PCM detects that the affected HO2S Heater current parameter is more than 3.125 amps or less than 0.25 amps.
-The above condition is met for 10 seconds.



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.

Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 1



If you have a digital multimeter you can compare the readings from the one on the other side. There's also a rather long diagnostic checklist from the service manual I can post if you want. Lmk.
 
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