"So, my P0401 error code seems to be the gas cap. I replaced it this morning. Drove about 50 miles in two drive cycles. Got back in the car a 3rd time and the check engine light did not come back on. I have driven it twice now with no check engine light. It was a $22 gas cap from the Toyota dealer. I don't know if that is your problem or not. The dealer service department person told me bluntly that this was not my problem and I was wasting my money buying this part. If the gas cap was the problem it would produce another a different error code. But, for my case, that doesn't appear true. I will keep driving it and we'll see."
换后，断开电瓶，踩刹车，按无电喇叭消码；再连上，开60 miles 以上（一个circle），如果换了灯还亮，第二步，去 dealer 买一个正宗 EGR valve，然后找一家车铺换，dealer 人工一般翻倍。
The code P0401 is listed among other possible codes. The repair again involves cleaning the EGR ports. Toyota Camry/Corolla: In Toyota Camry with the 2.2L engine, the code P0401 was often caused by a bad VSV (Vacuum Switching Valve) for the EGR, located under the intake at the back of the engine.
前几天我在这里发帖求助，关于 2000年 Toyota Camry engine check light亮了，查了Code是 P0401，在这里得到热心网友的好多建议帮助，结果还没等我采取措施发现那个灯自动灭了，很开心，不过好景不长，一两天后又亮了，我观察了一下，加满油后开150迈左右（大概不到半缸油）灯自动熄灭，再开到 200 迈左右 灯又亮了，我很好奇又试了一次，加满油再开，同样的情况又发生了，就是亮着的engine check light 每次在加满油后 开到 150迈左右熄灭， 至 200 左右迈重新亮
请问群里有朋友遇到过类似的情况吗？这对诊断engine check light的问题有帮助吗？
本人是车盲，先这里请教大家一下，可以心里有点底，这样去车行不至于被斩得太离谱.
谢谢大家看帖！
"So, my P0401 error code seems to be the gas cap. I replaced it this morning. Drove about 50 miles in two drive cycles. Got back in the car a 3rd time and the check engine light did not come back on. I have driven it twice now with no check engine light. It was a $22 gas cap from the Toyota dealer. I don't know if that is your problem or not. The dealer service department person told me bluntly that this was not my problem and I was wasting my money buying this part. If the gas cap was the problem it would produce another a different error code. But, for my case, that doesn't appear true. I will keep driving it and we'll see."
换后，断开电瓶，踩刹车，按无电喇叭消码；再连上，开60 miles 以上（一个circle），如果换了灯还亮，第二步，去 dealer 买一个正宗 EGR valve，然后找一家车铺换，dealer 人工一般翻倍。
三项一起做，修过后可平安5年
要看它的包装上有没有“Toyota”字样，logo，一般是红字。
go to Amazon to but a car monitor tool to reset the code.
油箱里的真空度到了一定的时候fuel tank cap没能让外面的空气进去，平衡气压。
The code P0401 is listed among other possible codes. The repair again involves cleaning the EGR ports. Toyota Camry/Corolla: In Toyota Camry with the 2.2L engine, the code P0401 was often caused by a bad VSV (Vacuum Switching Valve) for the EGR, located under the intake at the back of the engine.
以后朋友有问题可以用上
cap不能自动打开让外界的空气进去，我敢保证如果这是他拧开cap时会有扑哧一声。