I have 1999 protege lx, drove it to emission test recently. The test failed and said the catalyst, o2 sensor and EGR were not ready. I couldn't understand this, since it was six months ago that I cleaned the battery corrosion and reset the ECU. I'm pretty sure that I have driven more than 2000 miles (highway or local) after that.

Here is a bit about the history of my poor mazda.

About one year ago, the CEL light went on and threw codes P0171 and P0401, I cleared the code, the CEL went off and it passed the emission test.

Nine months ago, I bought a new upstream o2 sensor and had somebody replace the old one for me. After I drove for 50 miles, the CEL went on.

Six months ago, I cleaned the corrosion on the battery. The ECU was reset and the CEL went off.

One month ago I took the emission test. The day before the test, the CEL went on, stayed while I was driving, and went off the next time I started the car. Then I went to the test, and failed the test.

The CEL is still off now. However, I can read one code with the diagnostic tool. The code is P1170.

I went to do the emission test (after driving around 300 miles) yesterday, and failed the test again. It says that the Catalyst, O2 sensor and EGR are not ready.

Any ideas what could be the problem, and what can I do to help diagnose the problem? Thx a lot!

 

READ: https://www.mazdaforum.com/forum/new...ess-inc-31893/

 

Thanks a lot for the input. After reading the post on drive cycles, I think most likely it will be the battery problem, since it is more than 4 years old.

 

John: you have a vacuum leak.

 

Thx a lot for the input. I will check the vacuum leak today.
Btw, my car battery is almost five years old, so I think I'm also going to replace it anyway.
Will bring the updates later.

 

Read the Unofficial User's Guide in the sticky section. Most of it applies to your model year also.

 

Thx a lot for the link. I have read the user's guide, but I'm a newbie on automobile yet, so please excuse me if I ask some elementary question.

A few updates. I replaced the battery today and drove for around 50 miles on the highway. The CEL is on now. I check the code. It is still P1170, which could mean a lot of things.

On the highway, I notice something strange. The normal speed is 60mph, but sometimes it will decrease to 40mph. Even if I press the gas pedal really hard, it stays at 40mph, which seems to have no reaction to the gas pedal. Then after 10 to 15 seconds, the car went back to normal again. Moreover, When I press the gas pedal, the car usually stumbles slightly.

What could mostly like be the cause? Will check the vacuum leak tomorrow morning when the engine cools off.

Thx!

 

Btw, should I clear this code (since it does not give much useful information) and do another drive cycle, waiting for more specific codes to come out.

 

car won't pass with a cel light on.

 

I know that. The problem is: I looked up online and found there are a lot of reasons that could possibly cause the code 1170. It's a steep learning curve for me to do all the test. Is it possible that I clear the code, drive another cycle, and the car will throw out some specific codes?

Thx a lot!