One benefit of driving a cheap car (i.e., "cash car") is the fun of fixing it and the knowledge gained in that process. I love to know how things work and to tune them.
Yesterday, my car's "Service Engine Soon" light came on after I did a sudden acceleration in cruise mode. I freaked out - this was the first time I saw my engine light lit up. I thought my car might explode or catch fire.
A friend borrowed me his ODB-II reader and I got an error code P1404. I googled it and the cause is carbon deposit blocking my Exhaust Gas Recirculation (EGR) valve. This is reasonable that my car is 13 years old.
I found a very helpful video on YouTube about how to replace it. It doesn't seem to be difficult. So I decided to do by myself - why would I wait 1 hour in mechanics if it only takes me 5 minutes to fix by myself?
The EGR valve is at a place easy to reach. As shown in the figure blow, it's right under the air hose (marked by a red circle).
It is fixed by two 10mm hex nuts.
Replacing it is as easy as unscrewing two nuts, putting new EGR valve and EGR valve's gasket (you can get them at any auto parts store easily for about $140) on, and tightening the two nuts.
The EGR valve had lots of carbon deposit. In the picture below, both two channels (one of which has the valve controlled by a camshaft) looked completely dark.
The carbon deposit was very thick, about a few millimeters thick. I can easily scratch of large debris from the inside of the channels.
I was scared about what such large carbon debris can do to my engine. I think I made a right decision to replace the EGR valve.
In the end, I got the fun of fixing things and learned some knowledge about cars. I cannot get those if I let a mechanic fix it for me.
1. My "Service Engine Soon" light went off today before I replace the EGR valve - likely the carbon debris fell off.
2. Don't forget about the gasket between the valve and the tubes.
3. I also started the engine once without installing the valve to "cough" other carbon debris out.