what do the codes mean? what are my options?

2002 MAZDA 626
139 MILES
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HRPICCA111
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  • 1 POST
My engine light started sputtering and the engine light started blinking. It drives normal over like 40 mph but shakes when idling . The shaking is extreme. We took it to AutoZone for a codecheck and got the codes po421, po302, po316. That's ask they could tell us. It just started doing it out of the blue.
May 23, 2012 at 2:34 PM
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HMAC300
  • ✓ASE Certified Mechanic
  • 48,601 POSTS
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what engine ? Also those are misfire codes, check yoru fuel pressure first, then for vacuum leaks. the o421 code is catalytic effeiceincy and that may be due to the misfires. fuel pressure should be 30-37 psi
May 23, 2012 at 2:39 PM
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