Rep Power: 0

Trying to help fix my mother-in-law's 2001 Civic...

Symptoms...

MIL light - Code indicated upstream O2 sensor failure.
Non Honda shop replaces upstream O2 sensor with Bosch part
Car begins exhibiting cold start stalling...
After starting the car, it idles fine.
Put it in reverse and back out of the driveway.
Put it in drive and step on the accelerator peddle
Engine loses RPM and almost dies.
Then, it suddenly recovers and accelerates after a few seconds...

Condition never exists when the car is warm and it runs perfect at normal operating temperatures.

I went through the Idle Relearn procedure, thinking perhaps the non Honda shop didn't reset the ECM when replacing the upstream O2 sensor... That didn't fix the problem.

Car only has 67,000 easy miles on it...

Any ideas?

My thoughts are leaning toward TPS or perhaps an Engine Temperature Sensor, but the temp gauge seems to be functioning fine.

The other possibility is a bad O2 sensor from new...

Any help appreciated. Trying to fix it while visiting her on vacation...

 
Rep Power: 186

I'd start with replacing the Bosch sensor with an OEM Honda O2 sensor. These cars can be finicky about certain non-OEM parts and O2 sensors are one of them.

HTH

 
Rep Power: 518

Get rid of the Bosch sensor.

Use the same brand sensor the factory put in there. DENSO or NGK, whichever it was. Visit their websites to pick out the correct part number sensor, whichever brand it had from the factory.

 
Rep Power: 0

OK - I ordered an OEM NGK/NTK upstream sensor. We'll see if that fixes the problem... I'm not optimistic because the stalling only occurs when the car is in open loop mode, when the O2 sensor readings are being ignored...

I suppose if the O2 sensor temperature is what tells the ECM to enter and exit open loop mode, perhaps that could be the problem with the Bosch sensor.

The new sensor should arrive on Tuesday and I'll see if that fixes it...

 
Rep Power: 0

Follow-up...

Replaced the Bosch O2 sensor that was installed by a non-honda shop with an OEM NTK sensor...

Here is a comparison between the two...

Bosch on left NTK on right...


As you can see, a significant difference in sensor design.

Car has been driven twice from cold start since installation and the open loop stalling issue seems to be fixed.

I should know more definitely in a couple of more days after some additional cold starts...

Looks promising though...

 
Rep Power: 0

This solved the problem...

Do not install a Bosch O2 Sensor...

Get the NTK OEM one...

 
Rep Power: 518

There's a couple shops around me that repeatedly bring their headache cars to our shop, so many times it's because of discount (open on Sunday!) parts like this.
We keep telling them "quit trying to save money" but they just don't get it.