Ford Mustang Forum banner
Status
Not open for further replies.
1 - 4 of 4 Posts

·
Registered
Joined
·
730 Posts
Discussion Starter · #1 ·
My buddy has a 1988 Mustang with a 5.0 he's trying to get it back to original operation, he hooked up a diagnostic tool and it threw 4 codes at him.
21: Coolant Temp Sensor (ECT) Out of Range
42: EGO indicates always running rich
33: EGR valve not opening
18: Spark output circuit open


Anyone have an info?


 

·
Registered
Joined
·
73 Posts
My buddy has a 1988 Mustang with a 5.0 he's trying to get it back to original operation, he hooked up a diagnostic tool and it threw 4 codes at him.
21: Coolant Temp Sensor (ECT) Out of Range
42: EGO indicates always running rich
33: EGR valve not opening
18: Spark output circuit open

Anyone have an info?

42 can be caused by 21 or 18. Make sure the ECT is hooked up and if it is then replace it. After that pull the codes again. Also for 18 check the wiring on the coil to make sure it is right and in good shape.
 

·
Registered
Joined
·
2,808 Posts
42 is rich on one bank (right side), not both banks, so something is going on with that one side. Clogged Thermactor pipe or head on the side that is rich is usually the common problem. No EGR function will also cause a rich condition but it should be detected on both sides, as would a problem with the ECT sensor. The left bank's HEGO sensor may not be functioning correctly.

How many miles have the HEGO ("O2") sensors logged? If they have more than 50,000 miles, they would be the first thing I'd replace. Then I'd reset the fault codes (disconnect reader during KOER test code read-out), warm the engine up (drive it, not sitting idle), and test again.

Are the plugs, wires, cap, and rotor due for replacement?
 

·
Registered
Joined
·
46,010 Posts
Think Fox hit the target.
 
1 - 4 of 4 Posts
Status
Not open for further replies.
Top