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just did a tune up 2 days ago. And oil change yesterday. My Cats said they passed, but even with it saying they passed could it cause the 15mph test to fail? So my o2 being 0.1 can cause it to run to rich to fail it as well because its only says that at the 15mph not the 25mph. Thats why im confused.
Originally Posted by muellersfan
When was the last ignition system tune up?
The O2 value should always be zero. The 0.1 O2 value at 15 mph suggests a possible exhaust leak that makes the engine run rich.
NO levels are also a bit high, suggesting the cat may also be failing.
Check for an exhaust leak near or around the O2 sensor. For example, it's not uncommon for the header to develop a crack near the O2 sensor bung.
The somewhat high levels of both HC and NO suggest that the running rich condition is killing the cat. Fix before the cat is dead. Otherwise, the fix becomes more expensive.
okay ill check it out.. Thank you. Usually when i fail something, something else fails as well, so i have an idea of what its from.
Originally Posted by muellersfan
Check for an exhaust leak near or around the O2 sensor. It's not uncommon for the header to develop a crack near the O2 sensor bung.
The somewhat high HC and NO levels suggest that the running rich condition is killing the cat. Fix before the cat is dead. Otherwise, the fix becomes more expensive.
07-20-2019, 01:58 PM
Failed smog due to high HC at 15mph.
