Understanding the Check Engine Light: Causes and Solutions

So, I become depressed when I see the dashboard check engine light. Why? I’ve experienced a lot of car breakdowns over the years, which depresses me.

Some of the reasons include

Loose or Faulty Gas Cap – that is true for older vehicles, but new vehicles don’t have gas caps anymore.
Faulty Oxygen Sensor (O2 Sensor) – These sensors tattle on your engine when the air-fuel mixture just ain’t right.
Bad Catalytic Converter – Without it, your vehicle is basically a mobile polluter.
Failing Spark Plugs or Wires – No Spark? No vroom. Just sadness and misfires.
Mass Airflow Sensor Malfunction (MAF Sensor) – It measures air coming in. When it’s confused, so is your engine.
Bad Ignition Coil – The middleman between the batter and the spark plugs.. when he calls in sick, things go south.
Vacuum leak—those tiny little hose cracks = BIG dramatic engine light show.
Dead or Dying Battery?— A weak battery can freak out your car’s computer faster than a squirrel in traffic.
Bad EGR Valve (Exhaust Gas Recirculation)—It helps reduce emissions… and apparently your sanity when it fails.
Dirty or Clogged Fuel Injectors – Think of them as the tiny baristas for your engine. No coffee = No gas.
Thermostat Malfunction—Too hot? Too cold? YOur engine just wants to be Goldilocks perfect.
Transmission issues – Sometimes, engine lights double as warning lights for slipping gears or failing sensors.
Worn Timing Belt – Tick-Tock, the rubber clock… and if it snaps, oh honey, catastrophic.
Bad PCV Valve (Positive Crankcase Ventilation)— If it’s clogged, your engine basically starts choking on its own fumes.
Software or Computer Glitches – Even cars have their “Have you tried turning it off and back on again?” moments.
AND The Big ONE! The why I am writing this blog post Moment! It is PO325 – Knock Sensor 1 Circuit. In plain English – Your car’s brain thinks the knock sensor isn’t doing its job right. The Knock Sensor is like a tiny microphone bolted to your engine block. It listens for tiny knocks or pings (which happen when combustion inside the cylinders isn’t smooth, like a badly timed fireworks show.) If it hears knocking, it tells the computer, “Hey, back off the timing a little! Things are getting rough in here!” When does it fail? Well, your engine can run with bad timing because the computer isn’t being warned about knocking, and you might hear ticking, pinging, rattling or just feel a loss of power. Sometimes, you won’t feel much at all – but left alone, it can cause real engine damage.

The Knock sensor fell asleep at its post,
so the engine pings like a haunted ghost,
and though it tries to sing along,
the rhythm and timing are all wrong.

What causes PO325? 1. A dead or dying knock sensor, damaged wiring or loose connector to the sensor, and sometimes even engine sludge or build-up affecting the sensor’s ability to “hear”.

How to fix it? Usually means replacing the knock sensor, but the mechanic might recommend checking/fixing the wiring harness too if it looks crispy or chewed up.

You can change it yourself if you’re feeling do-it-yourself today, but it will be a bit more work because, like my husband’s Silverado, that sucker is concealed beneath the intake manifold. The sad trombone “Womp womp” is sounded.

My husband’s truck engine light turned on this morning as we were leaving for work, which is why I am revealing all of this. There is this “S” curve that goes down into the curve. His 2019 Silverado had a problem gaining power going up the hill this morning, and then “Boom!” the check engine light turned RED. Normally, our vehicles don’t have issues.

Oh, how I hate that pesky light. So many vehicles and so many troubles. His Silverado has 102,000 miles now. He has driven the heck out of that truck. I just pray that this doesn’t turn into an “Old Blue.” If you have listened to any of my songs, you probably hear my lyrics where I mention her. She is a 1984 GMC Sierra. She was old when we got her in the mid 1990’s but I’ll tell you one thing – she hauled a lot of yardsale stuff and made us a lot of money.

I think trucks can have personalities too. Old Blue was a gas guzzler. She had two tanks that only held about 12 gallons on each side. We were lucky if we got 10 miles to the gallon. And she seemed to know when we were going to come into money. Every year at tax time, that refund check was spent on her. If he got a bonus at work, that money was spent on her. But the one thing I am thankful for is -she didn’t break down when we were far from home.

Yup, she hauled a lot of stuff and now, the Silverado has become the New Old Blue except she’s dark gray. I just hope that these inanimate objects, to us that is, can’t talk to each other. Silver does get parked about 20 feet away from Old Blue everyday so may, I hope and pray, that Old Blue hasn’t rubbed off on her.