RubyC280

Hello, Now that I have resolved my transmission service woes, I have a new issue to sort out and would love some advice. Immediately after leaving repair shop after transmission fluid an filter were changed, my check engine light came on. Went back thinking it was a code relatedto the trans. Instead it was a secondary air injection fault code. Reset and erased code, light stayed off. Drove home 30 miles, and back to work the next day. Later in the day I went into the DD for coffee and left the car running . Came out and CEL was on again. Back to service tech, same code on the scanner. We were able to activate the air pump thru the scanner , so that is operating properly. I also can hear it come on from cold start and run for 20 seconds or so.

Any thoughts ? I'm sorry that I don't have the specific code to reference. The car is a 1997 C280 with 72k on it. Nice, well maintained car. Car is in Maine and temp range both days was about mid 50's, if that matters. I appreciate any advice you have.

xvvvz

Maybe one of the O2 sensors or its wires were damaged or came unplugged during the dropping of the transmission pan?

sickc43owner

check for lazy o2 sensor -there is a specific air injection test to verify
also common on 104 engine plugged ports on cylinder head-
if that is the case try clearing pipe out first then continuing to isolate fault
in head

RubyC280

Thanks for the tips. I've been driving the car daily now and have several hundred miles logged without the CEL coming on. I believe that a prolonged idle is nescessary cause the condition that throws the code. I also noticed the first time that a cyl #4 misfire code was thrown. I wonder if that fgures into the mix, or was a coincidence. Didn't have that code the second time, only the secondary air Inj code.

I will likley replace the easy stuff as a precaution ( O2 sensor and relay) and make sure the tubung is secure and clear. Beyond that, not too interested in pulling the head. Car runs great and delivers 28 mpg highway. I appreciate any add'l thoughts.

vinceC

The port that plugs is actually the EGR pipe where it enters the intake manifold. That throws a different code. O2 sensors won't throw a Secondary Air Injection code. Something else is going on.