On a 2003 Cadillac CTS, the high bank 2 sensor 2 (also known as the downstream oxygen sensor for bank 2) is located on the exhaust system. Specifically, it is positioned after the catalytic converter on the passenger side of the vehicle. To access it, you may need to lift the car and look under the exhaust piping. It's advisable to consult a repair manual or seek professional help if you're unfamiliar with working on vehicles.
it means knock sensor sensor 1 circuit high input (bank 1 or single sensor)
Trouble code P0138 means:O2 sensor circuit high voltage (Bank 1 Sensor 2)
HO2S Heater Control Circuit High (Bank 2 Sensor 2)symptomsOther than the MIL light illuminating you may not notice any performance issues.causeA short in the O2 sensor heater circuit or the sensor itselfA faulty O2 sensor heaterWiring or connectors are broken or frayed to the sensor or relayBad PCM or ECMThe fixCorrect wiring short or loose connector found in inspection.and/orReplace the bank 2 sensor 2, O2 sensorReplace PCM if circuit has failed and no wiring issues present, good O2 sensor
O2 sensor circuit high voltage (bank 1 sensor 2)
Oxygen (A/F) Sensor Heater Control Circuit High (Bank 1 Sensor 1)symptomsOther than the MIL light illuminating you may not notice any performance issues.causeA short in the O2 sensor heater circuit or the sensor itselfA faulty O2 sensor heaterWiring or connectors are broken or frayed to the sensor or relayBad PCM or ECMThe fixCorrect wiring short or loose connector found in inspection.and/orReplace the bank 1 sensor 2, O2 sensor
HO2S Heater Control Circuit High (Bank 1 Sensor 2)symptomsOther than the MIL light illuminating you may not notice any performance issues.causeA short in the O2 sensor heater circuit or the sensor itselfA faulty O2 sensor heaterWiring or connectors are broken or frayed to the sensor or relayBad PCM or ECMThe fixCorrect wiring short or loose connector found in inspection.and/orReplace the bank 1 sensor 2, O2 sensorReplace PCM if circuit has failed and no wiring issues present, good O2 sensor
Bank 1 driver side sensor 2 rear sensor. Good luck
HO2S Heater Control Circuit High (Bank 1 Sensor 2)symptomsOther than the MIL light illuminating you may not notice any performance issues.causeA short in the O2 sensor heater circuit or the sensor itselfA faulty O2 sensor heaterWiring or connectors are broken or frayed to the sensor or relayBad PCM or ECMThe fixCorrect wiring short or loose connector found in inspection.and/orReplace the bank 1 sensor 2, O2 sensorReplace PCM if circuit has failed and no wiring issues present, good O2 sensor
Oxygen (A/F) Sensor Heater Control Circuit High (Bank 2 Sensor 1)symptomsOther than the MIL light illuminating you may not notice any performance issues.causeA short in the O2 sensor heater circuit or the sensor itselfA faulty O2 sensor heaterWiring or connectors are broken or frayed to the sensor or relayBad PCM or ECMThe fixCorrect wiring short or loose connector found in inspection.and/orReplace the bank 2 sensor 1, O2 sensorReplace PCM if circuit has failed and no wiring issues present, good O2 sensor
Sensor 2 is after the catalytic converter.
HO2S Heater Control Circuit High (Bank 1 Sensor 2)symptomsOther than the MIL light illuminating you may not notice any performance issues.causeA short in the O2 sensor heater circuit or the sensor itselfA faulty O2 sensor heaterWiring or connectors are broken or frayed to the sensor or relayBad PCM or ECMThe fixCorrect wiring short or loose connector found in inspection.and/orReplace the bank 1 sensor 2, O2 sensorReplace PCM if circuit has failed and no wiring issues present, good O2 sensor
Cadillac cts 2003 star is a fancy and classical car which is sold for a high price. Only those who are wealthy enough to afford this expensive model, otherwise it would be impossible.