Check Engine light comes on and goes off (PO125 and PO441)

toyota
corolla

#1

For a few months, I have been getting check engine lights on my Toyota Corolla 2002. The check engine light often goes away by itself.

I took my car to a mechanic with a decent reputation after a couple weeks of the problem. He thought he fixed it and gave the car back to me. The check engine light kept coming back on, and I kept going back. The mechanic topped off the coolant, replaced certain hoses, host clamps, sensors and other parts (like the solenoid canister). After the fifth trip back (and eight weeks of time), he refunded my money.

The check engine light comes on and goes off. Right now with no check engine light on, I get codes P0125 and PO441 PD.

What will happen if I keep ignoring these check engine lights or the codes that persist when the check engine light is not on? I was thinking of going to another mechanic. I think I want to wait for a few more weeks to see if I notice a pattern. I do not drive that many miles each day (much less than average).


#2

As for the P0125, that’s very often caused by a thermostat stuck open, causing coolant temperature to NOT reach proper operating temperature within a specified time frame

I think you should go to another mechanic, because real diagnosis will be required, especially for P0441

https://www.obd-codes.com/p0441

On other brands, I’ve often seen that code caused by restricted fresh air vents for the evaporative emissions system. But there are other potential causes.

Are you having any problems filling up fuel . . . ?