Oxygen Sensor Codes Keep Coming Back
So you tested the oxygen sensors and they tested good or you have already replace one or both and yet the PCM keeps accusing them as being bad (which also means that the check engine light is back on).
When this happens, it's usually due to either a Rich condition or Lean condition that's being caused by some other component on the engine.
What sucks about this, is that whatever is causing the Rich or Lean condition is not present all of the time (specially when you're conducting the tests). This happens quite a bit. The strategy here is to wait a few days for the condition (that's causing the O2 sensor issues) to get worse. When this occurs, you'll be able to test it and solve it.
More Test Articles
There is one article that I recommend you take a look at that deals with testing a Lean condition. You can find this article here: Troubleshooting P0171 And P0174.
I've written quite a few 4.6L, 5.4L 'how to' tutorials that may help you troubleshoot the issues on your Ford car, pick up or SUV. You can find all at:
Here's a sample of the tutorials you'll find in this index:
- How To Test The Engine Compression (GM 4.3L, 5.0L, 5.7L).
- How To Test The Crank Sensor (GM 4.3L, 5.0L, 5.7L).
- How Can I Tell If My 4L60-E Transmission Is Bad?
- Troubleshooting A Blown Head Gasket (GM 4.3L, 5.0L, 5.7L).
- Shift Solenoid A And B Tests (GM 4.3L, 5.0L, 5.7L).
If this info saved the day, buy me a beer!
