I have a 1997 Toyota Corolla. My check engine light has been on. I tried to get my car smogged and it failed. I then got an oil/air filter change and just yesterday I replaced the EGR valve which was the result given after 2 diagnostic tests. The mechanic gave me my car and the check engine light was off, I've only driven about 5miles and the light is back on. I have to pass smog asap to register my vehicle. I plan on calling the mechanic back and telling him the light is on, but could it just be a sensor?
Let's start from the top. Your check engine light has been on and you took it to be smogged and you probably didn't know that the check engine light on is an automatic fail. So you get the oil/air filter changed without a reason, just because. Next, the diagnostic tests point to the EGR valve so you have a mechanic replace it, that is instead of having the mechanic figure out the real problem The mechanic could have replaced the valve or not, but you didn't get the old one from him, so you don't know if it's been replaced. He disconnected the battery so the light went out. Now it's back on so the problem isn't fixed. Could it be a sensor. Well, sure, but proper testing would tell you if it was. My GUESS is the EGR valve and ports where the EGR attaches just need to be cleaned out but without proper testing, that is just a guess. My suggestion is find a different mechanic, one who doesn't just disconnect the battery to turn the check engine light off, and don't go in telling this new mechanic what you think the problem is because you don't know.
The problem obviously wasn't the EGR valve. It is a solenoid that controls the EGR valve. A very common problem on Toyotas. Tell your mechanic to replace the EGR VSV solenoid. He will probably tell you that it tests fine, but that's the way they look when they fail. Just replace it. Google toyota egr vsv for verification. It is very easy to check flow, attach a vacuum pump to the valve and pump it up, if the engine stalls the valve is good, if the engine doesn't stall, the passage is probably plugged as the valves rarely fail.
All synthetic oil wont burn. But if the piston rings are shot and you'r failing on hydrocarbons, that's an expensive fix. Some states have an emissions waiver, maybe limited to older vehicles like yours, where if you show DMV you'v met their waiver threshold of spending on fixing the specific emissions prob that caused the failure and it still fails, they'l give you a pass till next inspection, or maybe only 1 yr. In some states it's not transferable when you sell and can only be used once per vehicle.
it could be a sensor ! the EGR code probably showed up because a sensor was interfering with the valve !
