Pontiac Repair: 91 Grand Prix SE 3.1, engine coolant, egr valve

Question
Hi Todd,

My car had been hesitating/stalling and generated OBD code 32.  I checked and cleaned a lot of carbon from the EGR valve and throttle body and hesitating/stalling is gone.  

However, during an extended idle (15 minutes) I noticed the service engine light had came on.  I am now getting four errors and don't know where to start.  The errors are 15, 32, 33 and 35.  These codes were not present before cleaning the EGR, and again, the car is running better than ever now!

What's your thoughts on this?  Thanks!

Answer
Hey Ronnny:

refresh my memory on this old car the egg on that year is vacuum operated right? if so when you have it running in park accelerate the engine if the valve is opening and closing the valve is bad. it should not apply while in park if it does then the valve is bad. Also if these other codes croped up after you took the valve off I would suspect the valve being bad as well. I would start there the code 15 I think is a temp sensor issue I havn't worked on an OBD car in years but I think the 15 is over or under temp for the engine coolant sensor. unplug the sensor and see if there is any corrosion in the plug if so replace the sensor and the connector. the sensors on those older ones had a tendency to seep coolant into the electrical part of the sensor. good luck :}