Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Check Engine Issue! HELP!

I just bought this used truck, 2005 Chevrolet Silverado 1500 extended cab. I noticed some shaking while in idle when I got it back home. The check engine light came on a day or two later, and I recently had a diagnostic test ran on it at the local AutoZone. It came up that I had a P0135 o2 sensor (bank 1 sensor 1) malfunction and a P0101 Mass Air Flow Sensor signal performance issue. The check engine light comes and goes. I stopped by Walmart for about 10 or 15 minutes and when I got back into the truck, the issues reoccured. For about a minute, the check engine light actually started blinking! And then went away and started running normal again. Its upper confusing. I bought some MAF cleaner to use on it tomorrow and figured that wouldn’t definitely clear up my issues, but I’m still wondering if the MAF sensor is enough to warrant the CEL to blink like that?! Any thoughts?

If the check engine light was blinking with the engine running, you have a SEVERE misfire . . . so bad, it could damage the catalytic converter

You need to get this diagnosed and repaired ASAP . . . do NOT keep driving it with the light blinking, or it can turn into a very expensive repair

I’ve heard that. But I did get it diagnosed literally 4 hours ago and it was the o2 sensor malfunction and MAF performance malfunction like i said. My question is if that’s enough to cause the blinking light? Considering it blinked and then disappeared as the engine began functioning normally again?

You got it diagnosed 4 hours ago

The check engine light was blinking AFTER that, correct?

If you were to have the codes scanned NOW, you’ll undoubtedly retrieve some misfire codes, in addition to those other codes you mentioned

Blinking means the computer thinks one or more cylinders are not exploding like they should. If blinking, it means it is happening a high % of the time. The engine computer can measure a misfire b/c it measures the acceleration of the crankshaft, and yours isn’t accelerating like it would if the gas explodes and pushed on the piston. The reason it’s critical to address this is b/c w/no explosion a full dose of gasoline could be sent out the cylinder and into the cat, which will quickly ruin it. A high $$$ repair.

Yes, diagnostic codes for a MAF and O2 sensor problem would be consistent with that problem. Both the MAF and the O2 sensor are involved in setting the air to fuel ratio, and the wrong ratio will cause no explosion and a misfire.

It’s unlikely both the MAF and O2 sensor are bad. Probably one or the other. The computer sometimes can’t tell. Generally you’d start with the lower P number. P101 is for the MAF, start with that.

A problematic crankshaft position sensor could cause this too.

Agree. The one cat on my Pontiac was $700 and there are two. GM was nice enough to pay for it though.

Thank you guys.