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

Check engine light was on then went off after a day

I have a 2004 Toyota Corolla.

Check engine light was on so I took the car to Midas they pulled a code (133) and they said its Oxygen Sensor is not working and cost to fix it would be around $350 including parts & labor, I thought it’s expensive and took the car to Auto Zone for second opinion, Auto zone confirmed that Oxygen Sensor might be having problem. Then I enquired in couple of places for the price to fix O2 sensor, all most all places I got the same quote i.e. around $350 to fix it.
And after a day or so check engine light went off. Check engine light was on for a day or so.

Now I am confused, is there a problem with Oxygen sensors? Should I still go ahead and fix these sensor or should I wait till Check engine light comes back again?

I’d Wait. If The CEL Comes Back Then Have It Checked To See If It’s The Same DTC (Diagnostic Trouble Code).

You shouldn’t have to pay to have it read. Most “national chain” auto parts stores will do it , gratis. Call or stop by one near you.

If you get P0133, again, look into it with a competent mechanic. I don’t know Toyotas, but compared with my cars that’s a really high cost to replace an O2 sensor.

Link for some help:

You could ask Santa for a stocking stuffer. For 50 bucks Santa can have one of his elves pick you up a DIY code reader from Sears or an auto parts store. Sears sells the Actron Pocket Scan for around that price. It’ll work on your car and almost anybody’s car that is a 96 or newer. They’re handy to have and you can check codes and leave them alone for the mechanic or clear them and turn off the CEL, your decision.


The O2 sensor might be fine, it just did its job. Is your car up to date on spark plug changes? New air filter and other normal maintenance? If not, invest the $350 is stuff like that. New plugs and air filter on a Corolla should be easy DIY job.

yes my car is up to date on maintenance. I did the oil change about 45 days ago. Even passed the emission test about 2 months back.

The problem could be that the O2 sensor is starting to become lazy. Or in other words, the cross-counts of the O2 sensor are starting to slow down.

Drive the vehicle and see if the Check Engine light comes back on again with the same code. If it does, replace the O2 sensor.


Tester has been around here a long time. His guesses are better than most of our carefully researched answers. He may be wrong, but the odds are on his side.

There is a software update for the engine ECU to correct this problem on the 2004 Corolla/Matrix.

From service bulletin T-EG017-07;

Under certain driving conditions, some 2004 model year Corolla and Matrix vehicles may
exhibit a M.I.L. “ON” condition with DTC P0133 (Oxygen Sensor Circuit Slow Response
[Bank 1 Sensor 1]). The Engine Control Module (ECM) (SAE term: Powertrain Control
Module/PCM) logic has been modified to improve this condition.

Good One, Nevada. Work Smart, Not Hard.
It’s Worth Checking Into To See If The Upgrade Was Done Or Needs To Be Done.

Chances are that the Midas shop didn’t do this prior to giving a $350 estimate.


Be aware that the dealer may very well want to charge more than the 0.8 hours listed in the technical service bulletin.
They may state those are labor times for warranty repairs.
Unless you somehow fall into the 8years/80K miles emissions warranty category.

Oh, one more thing: the dealer may also want to sell you a diagnosis on top of the TSB.

Thanks. I guess I dont have the warranty anymore because my vehicle has 132K on it.

One more question who are the best dealers around Waukesha county area? Where I can get this software updated.

If it isn’t interfering with your annual emissions test I won’t bother with the software update. There have been many vehicle built over the years found to have monitors that set a fault when it shouldn’t. For most it goes unnoticed until the conditions are just right for the glitch to occur.

If by chance a recall is issued for this or some reason on this car that requires a ECM update it will get done for free.

oh that’s great. My vehicle passed the emission test about 5 months back :slight_smile:

Anyways how to track the any future recall or ECM updates required, any useful URLs / Links?

On the Toyota web site you can inquire about campains/recalls. You can also update your ownership information so they can contact you in the event of a recall.

That website is useful, but it won’t mention any TSBs that apply to your car.

Did you add fuel injector cleaner to the gasoline tank recently or maybe seafoam, that stuff could trigger a CEL… a CEL doesn’t necessarily mean that something has gone bad. you may need to do a drive cycle so the system can reset.

I’ve used Seafoam for over 35 years and have yet see it cause a Check Engine light come on.


No I haven’t used seafoam or any other fuel injector cleaner to the gasoline tank. Good to know that “CEL doesn’t necessarily mean that something has gone bad”, I always thought that CEL on is bad :slight_smile:

I got a bad tank of gas a few months back. It caused the CEL to come on in my wife’s car. When the bad gas was gone so was the CEL. I reset it and it’s not been back.

Thank You all for ur advise and response.