2006 Cadillac DTS - Recurring P2A00 Code

O2 sensor has been changed several times but code P2A00 keeps coming back… from dealership to local mechanics shop. What is going on?.

My guess, wire or connector from th O2 sensor to the BCM.
I am not a mechanic, but a shop should have been able to figure that out.
Of course there are other problems that could cause the code.

P2A00 CADILLAC code possible causes

  1. Faulty Heated Oxygen Sensor Bank 1 Sensor 1
  2. Heated Oxygen Sensor Bank 1 Sensor 1 harness is open or shorted
  3. Heated Oxygen Sensor Bank 1 Sensor 1 circuit poor electrical connection
  4. Inappropriate fuel pressure
  5. Faulty fuel injectors Intake air leaks may be faulty
  6. Exhaust gas leaks

Read more: P2A00 CADILLAC Code O2 Sensor Performance Bank 1 Sensor 1

Changing it (problem #1) without finding the actual cause… could be one of #2 thru #6. Find a better mechanic.

My guess, something’s not airtight between the beginning of the engine intake path and the end of the exhaust pipe. All that stuff has to be perfectly air-tight, otherwise the O2 sensor system simply won’t work. On a 2006 one definite possibility is an exhaust system leak. Especially if this car has been used for a lot of short-trip type of driving. That leaves carbonic-acid in the exhaust pipes which will eventually corrode. This sort of leak can be difficult to find, but if diligently pursued by a knowledgeable shop, will eventually turn up.

A shop with a fully functional scan tool can monitor the O2 sensor signals as the engine is run. That’d help eliminate much of the guess-work.

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