DTC P0137 or P0157. Cadillac XLR 2004

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2004 🢒 XLR 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 DTC P0137 or P0157

Circuit Description

The heated oxygen sensor (HO2S) produces a voltage that varies between 100-900 mV under normal operating conditions. The engine control module (ECM) produces a bias voltage on the HO2S signal circuit of 420-480 mV. The reference ground for the sensor is provided through the ECM. The ECM monitors the signal voltage to determine if the exhaust is lean or rich. The oxygen sensor voltage is high when the exhaust is rich, and low when the exhaust is lean. The ECM constantly monitors the HO2S signal during the Closed Loop operation. If the ECM detects an HO2S voltage that stays below a specified value, or if the HO2S calculated resistance is below a specified value, DTC P0137 will set for bank 1 sensor 2, or DTC P0157 will set for bank 2 sensor 2.

Conditions for Running the DTC

•

DTCs P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0052, P0056, P0057, P0058, P0131, P0132, P0133, P0135, P0138, P0139, P0140, P0141, P0151, P0152, P0153, P0155, P0158, P0159, P0160, P0161, P1137, P1138, P1157, P1158, P2231, P2234, P2237, P2240, P2243, P2247, P2251, P2254, P2626, P2629, are not set.

•	The MAF Sensor parameter is more than 27.8 g/s.

•	The Engine Run Time parameter is more than 26 seconds.

Conditions for Setting the DTC

The ECM detects that the HO2S parameter is less than 2 mV for more than 5 seconds.

The ECM detects that the HO2S calculated resistance is less than 10 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.

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Controls Connector End Views or Engine Control Module Connector End Views

Did you perform the Diagnostic System Check-Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

Allow the engine to reach normal operating temperature. Refer to Scan Tool Data List .
Observe the HO2S Bank 1 Sensor 2 or HO2S Bank 2 Sensor 2 parameter, with a scan tool.

Is the voltage less than the specified value?

10 mV

Go to Step 4

Go to Step 3

Observe the Freeze Frame/Failure Records for this DTC.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 4

Go to Intermittent Conditions

Turn OFF the ignition.
Disconnect the affected heated oxygen sensor (HO2S).
Turn ON the ignition, with the engine OFF.
Observe the affected HO2S parameter with a scan tool.

Is the voltage less than the specified value?

25 mV

Go to Step 5

Go to Step 6

Test the HO2S high signal circuit for a short to ground or for a short to the HO2S low signal circuit. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 8

The HO2S may be detecting a lean exhaust condition. Inspect for one of the following conditions:

•	HO2S connector water intrusion

•	An exhaust leak between the HO2S and the engine--Refer to Exhaust Leakage in Engine Exhaust.

•	Vacuum leaks

•	Incorrect fuel pressure-- Refer to Fuel System Diagnosis .

•	Lean fuel injectors

•	An inaccurate mass air flow (MAF) sensor

Repair any of the above or similar engine conditions, as necessary.

Did you find and correct the condition?

Go to Step 11

Go to Step 7

Test for shorted terminals and poor connections at the HO2S. Refer to Testing for Intermittent Conditions and Poor Connections , Connector Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 9

Test for shorted terminals and poor connections at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 10

Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 .

Did you complete the replacement?

Go to Step 11

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

Go to Step 11

Clear the DTCs with a scan tool.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 12

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

System OK