Signal Too Low - Permanent Fault

ECM-2A2A REAR HEATED OXYGEN SENSOR (HO2S) PREHEATING
SIGNAL TOO LOW - PERMANENT FAULT

Checking wiring and components



Check Heated Oxygen Sensor (HO2S) resistance between # 1 and # 2.

Check signal cable between Heated Oxygen Sensor (HO2S) # 2 and Engine Control Module (ECM) # A35 (# A35) for a short-circuit to ground according to [1][2]Checking Wiring and Terminals. Permanent Fault

Remedy as necessary.

Other information
- Connecting the breakout box/accessing the control module Connecting the Breakout Box (ECM)
- To access/replace the heated oxygen sensor (HO2S), Adapter Wiring Switch, Replacing
- For resistance values, see Component Specifications. Specifications
- For information about signals, see Diagnostic Parameters and Pinout Values. Signal Description, ME7, B5XX4T


Verification



Hint: After carrying out the repair, check that the fault has been remedied.

- Ignition off.
- Reconnect connectors, reinstall components.
- Start the engine and let it idle.

Read the rear Heated Oxygen Sensor (HO2S) signal Diagnostic Trouble Code (DTC) status.
The text NOT READY is displayed if the diagnosis is underway.

Is FAULT NOT REGISTERED displayed?
Yes - Testing Complete.
No - Continue below.


Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed. Exit fault tracing for this diagnostic trouble code (DTC) or make another attempt.