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MikeD', Technician
Category: Car
Satisfied Customers: 696
Experience:  ASE Cert, AS Degree in Automotive Diagnostics
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1998 Mazda 626: Check Engine light..a gas cap..light went..oil changed

Resolved Question:

1998 Mazda 626 Check Engine light Code P1131 - last time this happened it was a gas cap - is this a repeat - I hae unhooked the positive battery cable and touched it to the negative battery post and the light went off for a while. After I had the oil changed it went off again.
Submitted: 9 years ago.
Category: Car
Expert:  MikeD' replied 9 years ago.

P1131 - System lean

You may have a vacuum leak causing this condition or a bad O2 sensor or Mass Air Flow Meter. You will have to hook up a scan tool or oscilloscope and spray the engine down with carb clean while monitoring the O2 conditions to find the vacuum leak. First, check all your vacuum hoses for cracks and your air intake plenum.

Customer: replied 9 years ago.
Reply to MikeD''s Post: Could that be related to the gas cap? Also it would appear I would either need an scan tool or an oscilloscope to proceed is that correct? Where I had my oil changed they checked for the P1131 code.
Expert:  MikeD' replied 9 years ago.

This code does not relate to your gas cap at all. That would be a P0441, 442, 455 code in the evaporative emissions system. Yes, you do need one of these tools and the shop that changed your oil should have one of them available unless it is just a quick lube place. They have limited tooling.

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