2000 Honda Civic DX rough starts when engine is cold

[tdowdy]

I have a 2000 Honda Civic DX that is just recently has been getting harder and harder to start when the engine is cold. Once started the engine idle is rough and falls all over itself. Once the engine warms up, say 3-4 minutes the engine runs just fine. Also there is no problem with any quick acceleration as the car preforms very well once the engine has warmed up. Today, with the outside air temp in the low teens it took a good 5 minutes of getting it started.

I have an ODBD II scanner and there are two codes P0117 and P0420. The P0420 has been on there for 6 months.

Any ideas on what could be the causing these cold/rough start problems?

 

[RonJ]

If you clear the codes, does P0117 return? If so, fixing code P0117 (ECT sensor circuit) should fix the starting problem.

The other code probably means the cat is dead.

 

[tdowdy]

checked P0117 code

I cleared the registered codes and restarted the car. I have driven the car for about 5 miles and neither code has come back on yet.

 

[tdowdy]

So, Do you think it is the ECTsensor? And if so, where is that located?

 

[RonJ]

Wait to see if the any codes return with more driving.

 

[tdowdy]

Tried another cold start and still have the problem. I ended up picking up a new ECT sensor and did the install. I will try in a couple of hours once the engine cools down again.

 

[tdowdy]

Issue Fixed

Replacing that ECT sensor fixed my problem. Thanks for your input.