Miata MX-5

Check Engine Light Due to Improperly Manufactured Threads on Fuel Filler Pipe on Mazda Miata MX-5

Problem Description and Possible Solution

Some models may have a problem where the Check Engine light illuminates indicating an improperly tightened fuel cap. Due to improperly manufactured threads on the fuel filler pipe, the filler pipe may need to be replaced.

Problem Data
RepairPal Verified
Average mileage: 37,011 (4,000–145,000)
10 model years affected: 1994, 1999, 2006, 2007, more2008, 2009, 2010, 2012, 2013, 2014
44 people reported this problem
Viewing 1 - 20 of 21 comments
check engine light comes on. Dealer Service shows problems with fuel filler pipe but this vin# not included in recall. Why?
Check engine light came on this morning. Opened then tightly closed fuel filler cap, but had no effect.
Starting when I bought this car used with 37000 miles on it I get a check engine light the code set is a loose gas cap and has now occurred 3 times in the last 9000 miles. I know that the cap has been reinstalled properly after refueling and I have to bring the car to my mechanic to reset the engine light, the cap is loose when the light comes on.
Check engine light comes on. The system code says a loose gas cap. the cap even gets so loose that it will come off in your hand, even if you tighten it. I think it must be the fuel filler pipe, the threads must be bad. Next step is to talk to the dealer.
Check engine light illuminates often. Code says evap system leak. I just clear the code, retighten the cap and keep going. It happens about once a month.
got code p0442 and replaced fuel cap with new redesigned mazda one. light stayed off for 100 mile and came on again. cap was loose. dealer will not fix.
Check engine light came on. The code read by the service center pointed to the fuel filler cap. It was replaced and the problem went away.
Taken the car in to the dealership 3xs. They continue to maintain that the light is on because I am not "tightening the gas cap enough"! I KNOW how to tighten a gas cap!! Today I was humiliated while the service consultant explained that "if" I am telling them the truth, they will do me a "favor" by replacing the gas cap, because it is clearly the owner's mistake and not theirs! Grrrrrr
this happened with my 2012 as well. ya think Mazda would have made it right by now. need to buy another gas cap for my 2014 .. ridiculous!
check engine light on, checked gas cap and will not stay tight when screwed down as per manual. Cap looks to not be worn, similar to new cap.
Check engine light has been on now for several weeks. I went to a parts store and ordered a new gas cap. Put the new gas cap on and CEL is still on. Next step is to go purchase a gas cap from the MAZDA dealership.
engine light comes on and stays on, the fuel filler cap is loose, I tighten it and in a few days it comes loose again all on its own.