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Occasionally6 · 07-06-2013, 12:27 AM

Yes, O2 sensor. They have a life of about 50 000 miles, give or take a bit.

Maybe look at the basics like spark plugs and ignition leads. The 'plugs will typically have a life of about 30 000 miles. The leads are replace as needed. When you buy your DMM, you can check their resistance. They should be < 3000 Ohms per ft.

An ignition misfire might or might not show up as a fault code. If it's happening, it can be hard on the cat. so it's worth checking the leads and the 'plugs are cheap, if there's any doubt.

Engine oil can load up with fuel over time so, an oil change can help sometimes.

If you have a fuel tank vent system with a Carbon canister purge valve, it's possible that may be leaking.

If the engine has wear on it and is burning oil that will increase the HC. (A higher viscosity oil might get you past the test if it's marginal.)

07-06-2013, 12:27 AM	#4 (permalink)
Occasionally6 Master EcoModder Join Date: Apr 2013 Location: World Posts: 385 Thanks: 82 Thanked 82 Times in 67 Posts	Yes, O2 sensor. They have a life of about 50 000 miles, give or take a bit. Maybe look at the basics like spark plugs and ignition leads. The 'plugs will typically have a life of about 30 000 miles. The leads are replace as needed. When you buy your DMM, you can check their resistance. They should be < 3000 Ohms per ft. An ignition misfire might or might not show up as a fault code. If it's happening, it can be hard on the cat. so it's worth checking the leads and the 'plugs are cheap, if there's any doubt. Engine oil can load up with fuel over time so, an oil change can help sometimes. If you have a fuel tank vent system with a Carbon canister purge valve, it's possible that may be leaking. If the engine has wear on it and is burning oil that will increase the HC. (A higher viscosity oil might get you past the test if it's marginal.) Last edited by Occasionally6; 07-06-2013 at 12:33 AM..