I have a 1996 Blazer that runs and drives great. The other day I took it on about an hour round trip and it threw me some error codes after driving about 45mins. I usually only drive this about 10mins to work and back every day and its never given me any issues or codes. The only known problems I have that I have been putting off is the cat has rattling inside it and I need to replace one of the cross bearings in the driveshaft eventually. I do not have any existing engine or trans issues.

1st code I have is P0700 Which is a transmission fault code and usually followed by another trans code, I think its also supposed to be in limp mode too but it isn't and drives completely normal.

2nd code is P1406 Which is an EGR code, as long as its faulted and closed I do not care about this one very much, If anything I will buy the block off plate if its faulted open. How do I check what position it is in?

3rd code is P0174 which is my O2 sensor bank 2 too lean which could mean my EGR is stuck closed
4th code is P0171 which is O2 sensor 1 too lean which I guess could also lead to EGR stuck closed

Any advice on these codes? It seems to me for the last 3 codes I should address the EGR valve to see if it is stuck in a position. As far as the 1st code though it did not have a follow-up trans code so I am just going to clear it and see if it comes back. I have a live scanner as well that I have not connected to the vehicle to see if it can tell me any more information.

 

if the EGR is involved in your lean codes then it should be stuck open. Why don’t you look for carbon deposits and try cleaning or replacing it. If the EGR valve is not related then there is a list of potential causes where a vacuum leak is at the top of the list. We can go down that path if you like.

George

 

On my '95 when the EGR valve got stuck open due to carbon deposits, the idle got rough. Engine ran ok when driving, except taking-off from stops.
Removing the EGR valve is pretty easy, two 10mm bolts holds it in place. I had to remove it several times to clean it over the years I had it. Suggest a new gasket.

 

If I remove it and measure the distance between the bolts and then make a block off plate will that eliminate this issue from happening again? I don't care about the CEL staying on or anything.

 

I won’t be able to help you with that, as I have never defeated an emissions control device. I’ll bow out and defer to someone who has experience with this.

George

 

As George said, the EGR is easy to clean and would only cost the price of a gasket and a little time. I also remember some option about a metal screen for the EGR valve that would reduce the carbon build up. Take a look at the TSB's on your year to see if that would help you, This screen would help you avoid the carbon build up on the EGR valve. Then you would have a legal engine and a less frequent EGR cleaning interval. The ultimate solution.

 

Blocking off an EGR you would have to know if it is taken into account to counter spark-knock by the ECU. A missing EGR could damage the engine or result in poor performance under some driving conditions.