I have a '94 Z28 that has been experiencing a "Service Engine Soon" light when driving around after warm up. I was able to get a OBD I reading this morning which resulted in a code 45 "Mass Airflow System Failure." The tech looked at the fuse/relay box in the engine compartment and found that the 20A "Air Pump" fuse was blown. He replaced it and I drove it down the street about a 1/2 block and the SES light came on again. I checked the fuse and it was blown again. Next, I replaced the "Air Pump" relay just to rule that out and installed a new fuse which blew again after about a block. I don't think that the fuse problem is being caused by a direct short in the wiring. The engine seems to be running great. Starts on the first hit. The only noticeable thing about this problem is that when the SES light comes on, the cooling fans kick into high speed. Makes the car sound like a jet is coming down the road. The cooling system is fresh and the temp gauge says everything is O.K. Is the "Mass Airflow Sensor" the culprit? Anyone know?

Thanks for any help,

John

 

Since noone else has replied I will chime in.

I think you have your DTC codes confused. A code 45 is "Left 02 rich". A MAF Fail is a 48. Try and verify these and which you actually have.

If you are indeed having issues with your Air you may want to just delete all that junk. Very common thing to do.

 

Thank you so much for replying to my post.
It is possible that I got the codes mixed. What I know for sure is that the OBDI reader clearly stated on the right side of its display: "Mass Airflow System Failure." Whether it was a 45 or 48, I will try to find out. If indeed it was a 45, is that MAS related, and would that cause the "Air Pump" fuse to blow? Also, I'm not sure I follow what you mean by "delete all that junk." Basically, I need to get the car smogged. ( I'm in CA) and I can't pass smog and get new tags until I get that SES light to stay off.

Thanks again for any advice.

 

If the light comes on after the car warms up (open to closed loop) I would suspect the MAF sensor. Check the wiring and voltage. If you knew someone with the same car, you could swap MAF and see what happens.

 

Thank you for that advice. It would make sense that a bad MAF Sensor could cause a short when it kicked in from open to closed loop thereby blowing the fuse. I will test this out with a Firebird friend.

Thanks again.

 

To prevent the AIR pump fuse from blowing, unhook the wire harness connector from the AIR pump, then replace the fuse. That will avoid any code for the AIR pump not being connected. Then drive it and see if the SES light comes back on, and get it scanned again, with an accurate code # and description.

If it is a problem with the MAF, you have to unplug the MAF sensor, put a new fuse in the circuit, check to insure that with the key on you have +12V at the pink wire on the MAF harness connector, when measured to the black/white ground wire on the connector. The MAF is fed off the same fuse as several other items, so one of those could be causing a problem as well. On Shoebox's page, he has the 95 wiring diagrams, and it shows in one location that the MAF sensor is fed off Fuse #5, and in another location that Fuse #4 supplies the MAF sensor, PCM, fuel pump relay and theft deterent module. You would have to find a 94 wiring diagram, to see what else is on the MAF fuse circuit.

They list what is on the fuses in the Owner's Manual, but I looked at the online version for the 94 Camaro, and it doesn't specifically mention the MAF sensor.