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Home/DTC Codes/Cadillac/SRX/2007-2007 3.6L V6/P0040
P0040

O2 Sensor Signals Swapped Bank 1 Sensor 1 / Bank 2 Sensor 1

2007-2007 Cadillac SRX 3.6L V6

Moderate SeverityPowertrainGeneric (SAE)

The 2007 Cadillac SRX is equipped with a 3.6L V6 engine. Below you'll find detailed p0040 diagnostic code information including labor time estimates, cost ranges, and technician notes specific to this engine configuration.

Description

The PCM has determined that the upstream O2 sensor signals for Bank 1 and Bank 2 are swapped, likely due to incorrect wiring after sensor replacement.

Symptoms

  • Check Engine Light
  • Poor fuel economy
  • Rough running
  • Failed emissions

Common Causes

  • O2 sensor connectors swapped after service
  • Wiring crossed between banks
  • Incorrect sensor installation

Diagnostic Steps

  1. Verify which O2 sensor is connected to which bank
  2. Trace wiring from each sensor to PCM connector
  3. Check for crossed connectors

Repair Notes

Swap the sensor connectors to the correct banks.

Related Codes

P0041O2 Sensor Signals Swapped Bank 1 Sensor 2 / Bank 2 Sensor 2P0130O2 Sensor Circuit Bank 1 Sensor 1P0150O2 Sensor Circuit Bank 2 Sensor 1

Other Powertrain Codes

P0040 on Other Vehicles

Cadillac ATS

2013-2013 2.0L Turbo I4

Cadillac ATS

2013-2013 2.5L I4

Cadillac ATS

2013-2013 3.6L V6

Cadillac ATS

2014-2014 2.0L Turbo I4

Cadillac ATS

2014-2014 2.5L I4

Cadillac ATS

2014-2014 3.6L V6

Cadillac ATS

2015-2015 2.0L Turbo I4

Cadillac ATS

2015-2015 2.5L I4

Common Questions

What does code P0040 mean on a 2007-2007 Cadillac SRX?

P0040 stands for "O2 Sensor Signals Swapped Bank 1 Sensor 1 / Bank 2 Sensor 1". The PCM has determined that the upstream O2 sensor signals for Bank 1 and Bank 2 are swapped, likely due to incorrect wiring after sensor replacement.

What are the symptoms of P0040 on a Cadillac SRX?

Common symptoms of P0040 include: Check Engine Light, Poor fuel economy, Rough running, Failed emissions.

What causes P0040 on a 2007-2007 Cadillac SRX?

Common causes of P0040 include: O2 sensor connectors swapped after service, Wiring crossed between banks, Incorrect sensor installation.

Last updated: March 2026

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