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![lowejah](themes/aaAle/images/interface/profile-pic-placeholder.47cf740a.png)
Hi there. I have an old Subaru Legacy 1998 which has done 340K and still running well. The "check engine" sign kept coming on so took it to Subaru dealer who fiddled around and said it was prob because I was using 91 fuel rather than 98. So I started using 98. The sign went away but still comes up intermittently. I am tempted to go back to using 91 due to my limited budget but am scared it will cause engine damage. What would you recommend (apart from a new car!!) Cheers
![Anon](/assets/Uploads/_resampled/ScaleWidthWyI3NSJd/CMSThumbnail-SetWidth75-aa-avatar.png?m=1518003100)
If the Subaru dealer recommends the exclusive use of 98-octane fuel then it's best to stick with the premium juice. The problem could possibly be a faulty exhaust O2 sensor or due to the fitment of an aftermarket (performance) air filter for the engine - we have heard of cases where the intake airflow measurement is incorrect due to this and causes the vehicle to run lean which can be devastating to the engine in the long run. If the light is coming on then you need to get it back to a mechanic who can diagnose and repair the fault.
![lowejah](themes/aaAle/images/interface/profile-pic-placeholder.47cf740a.png)
sound advice - will book it in again to Subaru dealer...
Many thanks