Nope. There's well over 2,000 things the Engine Computer watches or tests periodically. When a defect occurs, the computer sets a diagnostic fault code. Those codes have different levels of severity. About half of those codes refer to something that could adversely affect emissions. Those are the codes that turn on the Check Engine light.
The place to start is by having the fault codes read and recorded. The people at most auto parts stores will do that for you for free, but be aware they're there to sell parts. Fault codes never say to replace a part or that a sensor or other part is bad. Before we spend our customer's money on a part, when one is referenced in a fault code, first we do electrical tests on that circuit. These include testing for broken or grounded wires, corroded connector terminals, and mechanical problems associated with any parts mentioned. Roughly half of the time a sensor mentioned in a fault code is actually the cause of that code, but it's just as likely a new part isn't the answer. Sometimes, based on past history, we can make an educated guess as to whether a new sensor is the best suspect.
The worst fault codes cause the Check Engine light to flash. No need to bail out of the window, but it should be considered almost as serious as the "Oil" warning light. Stop the engine as soon as safely possible. The flashing light means too much unburned fuel is going into the exhaust system where it will burn in the catalytic converter and overheat it. Ignoring that can lead to a very expensive repair.
One step below that is when the Check Engine light is on steady anytime the engine is running. That can include an intermittent problem that is not currently acting up.
The next step down in severity is again, for an intermittent problem, the light will "latch" on when the problem occurs, then, if the problem clears up temporarily, the light remains on during the rest of that drive cycle. It will be off the next time you start the engine, and remain off until the problem occurs again.
For the least severe problems, if it clears up while driving, the light will turn off, and only turn back on if the problem occurs again.
As I mentioned, the least serious codes have nothing to do with emissions, and they don't turn the Check Engine light on. Those codes are still in memory, so it's necessary to read codes even when the Check Engine light isn't on.
Most scanners and simple code readers will give you a description of the problem,, but it's more valuable to get the actual fault code number. With that, you can go here:
https://www.2carpros.com/trouble_codes/obd2/p0400
to see the definitions, or I can interpret them for you. I can also find the diagnostic charts for most codes, specific to your model.
You can also check out this article on how we get the fault codes:
https://www.2carpros.com/articles/can-scan-controller-area-network-easy
Let me know when you have those code number(s).
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Friday, November 29th, 2024 AT 3:09 PM
