1997 Tacoma check engine light on

looked in the manual for possible problems and it all it says is “take to dealer”.

Are there certain things I can check myself, first? Brake fluid, oil, etc.?

Looking for any recommendations before dropping $$$. Thanks!

~ Deb

Many local psrts stores will read the fault codes for free. Get the codes and post them here along with the mileage, the maintenance history, and any other symptoms you are or have been exhibiting.

You should check your fluids regularly anyway, but that’s not going to help clear your codes.

Chances are that you’ll not be able to find to problem just looking at things. The computer has detected a problem and set a trouble code. There are hundreds of codes, and no way of determining the problem until the code is read.

However, a lot of auto parts stores, like Advance Auto, Autozone, O’Reilly’s, will read the code for free. All cars and trucks made after 1996 use a unified code system, and a typical ODB-II code reader can read these codes no matter the brand or type.

If you get the code, in a format like P0131, and post it here, there are many people that can give you advise on how to fix it.

thanks for the help! I am calling local auto stores this morning to see who can read it. I really appreciate it!

mountain bike & knuckles…thank you.

I called some places and one store said that in California they are not allowed to do that anymore - has to be a licensed mechanic. And some local service stations charge $30 to do it. Seem true to you?

Anyway…called my mechanic (worked on it for years) and he said first up - check the gas cap and make sure it’s tight. He said since the light is steady, it is good (and most likely a minor issue) and should be okay to drive. If it flashes, then it’s more major and needs to be looked at sooner. He did mention, though if it is the gas cap, the computer could still take 3 days or so to clear since it wants to make sure the issue is truly fixed. I had no idea how sophisticated cars are these days!

I learned from hubby that he dropped the gas cap recently and something broke on it, so let’s hope that is all this is.

Thanks again and any further thoughts are always welcome.

Wow. A licensed mechanic is necessary just to read codes? A mechanic needs to be licensed? I sympathize with Californians.

He’s right in that a gas cap can cause a light. If so, the codes would read as an EVAP system failure. Your car has a system to prevent the release of hydrocarbons into the atmosphere from evaporation of gasoline. It’s called an EVAP system, short for Evaporative Emissions Control System. Your gas tank vents into an activated charcoal bed, the trapped hydrocarbon molecules then ingested into your car’s intake through a purge valve when you start the car and burned with the gas. The feds require a system to monitor the EVAP system for defects, so if your gas cap leaks to the outside air the vacuum sensor in the tank will tell the ECU that it’s leaking and trip a code.

Hopefully that’s all that’s wrong. Post back with the reaults.

Sincere best.

Hey guys…it’s been a while, but I have some new info.

I bought a new gas cap about a week ago, but the check engine light remained on. Went in for a smog check today and the guy told me he doubted it would pass given that the light was on. Lucky for me, he ran a diagnostics for free and gave me the printout. Then, he cleared the multiple codes and said drive it for 30 miles and see if the light comes back on (with the hope I will bring it to him if it needs servicing). Should this be continuous driving or can little trips make up the miles?

Thought I would run the codes by you:

Emissions Related DTCs Mode 3

P0300 Random Multiple cyinder misfire detected

P0301 Cylinder 1 misfire detected

P0304 Cylinder 4 misfire detected

P0440 EVAP Control system malfunction

Continuously Monitored systems DTCs Mode 7

P0304 Cylneder 4 misfire

P0440 EVAP Control system

Then he asked when the last time was we had spark plugs, cables changed, etc.

Looking forward to any input/advice.

Always appreciative,


Well - when was the last time you got new plugs and wires?

over 7 years to the best of my knowledge. Regardless of codes, seems a tune up of sorts is in order. I haven’t been in charge of this vehicle until recently.

With misfire problems the simplest place to start is with the ignition system - and the simplest part of that would be plugs and wires.

But by the sounds of it - yes a general tune up of sorts would be in order including air & fuel filters.

One thing you might think about - esp. since it sounds like maybe the maintenance has not been great - is to just have someone check the compression before you start having work done on it. This can alert you to any serious mechanical issues. If you know someone who is half-way handy this is not hard to do, or a shop can do it for not much $$. Of course, plugs & wires aren’t complicated either.

If you’re going to be paying someone else to do work on it, just find a good, local, independent (non-corporate chain) shop and ask what they recommend.

thanks so much for the info. I am so happy to have people help me learn as I go along.

Much appreciated!

~ D

An OBD II Code Reader is what you need to read and erase those trouble codes. It just plugs into a connector at the edge of the lower dash, and you push a couple of buttons to reveal the codes, and a button to erase the codes. An OBDII Code Reader costs $60 at any auto parts store, and, you can use it as many times as you wish.
The P0300 is for misfires on all engine cylinders, and P0304 is for misfire on cylinder #4. The P0440 might be caused by a poor gas cap seal, or, it might be something else in the Evaporative Emissions Control System.
New spark plugs will definitely help with the misfires. I don’t think your engine has spark plug wires. The parts photograph looks like it has ignition coils on spark plugs (COP = Coil On Plug).
Change the spark plugs. Erase the trouble codes with the OBDII Code Reader. Drive the truck for 3 or 4 trips. If the check engine light comes on, read the codes with your handy, dandy, code reader, and let your mechanic, or us, know what the trouble codes are.

Has the CEL come back on yet??