Check engine light

[Metsfan785]

Hi everyone hopefully I can get some help here I have a 07 tahoe with a check engine light on originally it was because the 02 sensors where bad I replaced all but check engine light will not turn off took to my local mechanic he cleared the codes but still will not turn off he thinks it could be a computer issue any ideas of what it could be or any suggestions on how to get rid of light thanks in advance

 

[HiHoeSilver]

What code (s) is it throwing?

 

[Rocket Man]

You mean the light turns off after clearing the codes but comes back on, right? You need to make a note of any codes before you erase them, to see if they're the same ones that return. Plus then you can look them up to see what they mean, and so we can help.

 

[Metsfan785]

You mean the light turns off after clearing the codes but comes back on, right? You need to make a note of any codes before you erase them, to see if they're the same ones that return. Plus then you can look them up to see what they mean, and so we can help.

It was reading the same code for o2 sensor and yes it would come back on but took to my local mechanic he looked at it said that 02 sensor are good which I expected since I changed all of them but the issue I am having is that now that codes are cleared the check engine light is still on when the car is in the on position not started and I can not pass my inspection

 

[Metsfan785]

What code (s) is it throwing?

It was throwing code p0420

 

[Rocket Man]

p0420 is catalyst efficiency which means either bad O2 sensor or bad catalytic converter. You probably have a cat (or more likely both) that's going out. Your O2 sensors check the o2 levels before the cats and then after the cats, to see if they're working right. Your mechanic should be able to check them.

 

[HiHoeSilver]

p0420 is catalyst efficiency which means either bad O2 sensor or bad catalytic converter. You probably have a cat (or more likely both) that's going out. Your O2 sensors check the o2 levels before the cats and then after the cats, to see if they're working right. Your mechanic should be able to check them.

True dat. So many people just say it's a bad sensor. It is certainly possible that the sensor is working just fine and throwing the code for good reason. That's its job, after all.

 

[Metsfan785]

So it through a code today p0054 which I have had once before

 

[Rocket Man]

So it through a code today p0054 which I have had once before

That's a bank 1 (driver side) downstream O2 sensor problem so I'd say once again it's pointing to a bad cat or the sensor is unplugged. You can Google these codes and read up on them yourself so you'll have more info.