P0126 after EGR delete

[Stinow]

Hi all,

Last week I removed my EGR and installed the Damond Motorsports EGR Valve delete kit (or actually EGR Full removal kit, but noticed that a previous owner already added the small extra plate).

After I while I got the P0126 again. Had this code about 3 months ago, then I replaced the thermostat (it was always open) and the code went away.

I made sure there is enough coolant and 'bled' (?) the system so there should be no air bubbles.

Anyone has any idea which steps I could take to debug this issue? Are there some things I can log using the software?

Thanks a LOT in advance!

[mituc]

With the EGR removed, blocked or not, this code appears in two situations:
1. thermostat stuck open;
2. failing ECT sensor;
Or of course both, which may be the case for you.

[Stinow]

Thanks!

Well, I replaced the thermostat about 3 months ago and worked perfect then (before that I had the same code).
Today I replaced the sensor, but still the same. No overheating, just slowwwwwly getting warmer and temp dips as well.

Buy another thermostat? Or is there something I can log?

This weekend I was planning to go on a first ever 'tour' with some car lovers. Is it safe to drive still? Or would you advise to have this fixed first?

Thanks!

[mituc]

Buy another thermostat? Or is there something I can log?

Was the thermostat OEM? If it was not OEM then you have basically two problems:
1. during winter these aftermarket thermostats will open sooner and will lead to issues like the one you have;
2. even though they open sooner, they allow for less flow and that will be obvious during summer when the ECTs will tend to be higher than you've had with the OEM thermostat.

These are the potential issues that you can have because of the thermostat, and some of the symptoms match meaning that replacing your thermostat with the right part may fix the issue.

However, removing the EGR (why?) will deprive the cooling (and heating) system of one heating source placed right on the exhaust side of the engine which is pretty efficient at recovering lost heat especially in the first few minutes after a cold start during the cold season. So it may be just the effect of removing the EGR even though I did not hear about anyone getting a coolant temp code after that.

[Stinow]

Thanks a lot for your advice!

The only one I had available at that time was aftermarket. I'm guessing that is indeed the problem.

Tomorrow morning I will replace it with a brand new Mazda OEM thermostat.

Will post here how it works out after several 100's of KM.

Thanks again!

[Stinow]

Well, replaced it with the OEM version. Now driven about 1300km since then, and code is gone, light is gone and running well!

Thx a lot Mituc!

[mituc]

Epic WIN! I'm glad you figured it out!
Now it's time for more power! Versa tune it FTW!