Hi people!

I am really not a mechanic, but i try to do what i can myself - and this time i am a bit stuck. I have searched the web and i HAVE found a few threads with some people expriencing the same or similar issues. However they all end in the same way - with the problem probably being resolved but the author does not update the thread. So i here by promise to update this one when the issue is resolved, so that it may help some other poor guy or girl in the future. Also im Swedish, so please have some tolerance with my spelling and grammar.

I will try do describe the car and the problems as detailed as i can, maby most of it is unrelated. But after having owned lots of used cars i am just not surprised anymore to learn how the strangest things can be related...

Ok, so for about a month ago i bought a Mazda 5 2.0 MZR-CD, manual, 143hk, generation CR from 2007.

Drove it home and all was fine. Then shortly after i was hospitalized and had surgery to my loungs (yes, i do realize that this is actually unrelated ) and the car stood for about 14 days.

Got home and started using the car every day. Then the cold hit Sweden and I usually only drive shorter ranges, so the DPF light started flashing.
I have a iCarSoft CR Max diagnostics tool so i plugged it in and ran the DPF regeneration program. Took about 30-40 minutes and after that the light where off and the the car ran just fine again.

Then I installed a led ramp by using a cable that connected between the headlight bulb and the battery with a "smart relay" in between that senses if the car uses a signal for high beams or if it (like the Mazda) uses ground control to switch between high and low. Seems to be working just fine.

After this Sweden got a really cold wheater front with temperatures reaching as low as minus 30 degrees celsius where I lived. And i learned that i have a faulty sensor/stuck switch in the driver door which led the car to believe the door was open even though it was closed. This resulted in the lights beeing on inside the car over the night and completely drained the battery.

Poped the hood to charge the battery and noted that the coolant fluid had turned to slush during the night. I did NOT start the car while the coolant was frozen!
I connected the charger and the battery indicated fully charged after about 30 minutes, so i figured the battery was toast - but it did give enough juice to start and run the car so at this point i let it be.

So i put an air heater fan in the engine compartment and plugged in the block heater to defrost the engine. Let that run for about 8 hours.
When the coolant was fluid again i measured the fluid and it had a freezing point of about minus 18 degrees celsius. Emptied about a litre of fluid and topped it off with som concentrated glycol, remeasured and the coolant is now fine down to about minus 32 degrees.

And now this is where the fun starts... Next time i used the car the DPF started blinking, the check engine light came on solid as well as the TCS/DCS light and the car went into limp mode.

The TCS/DCS did infact not work, ABS seems to work fine though when i apply brakes on slippery road.
I pulled the codes and got:

Powertrain - P0548-FF - Exhaust Gas Temperature Sensor Circuit Low, Bank 2 Sensor 1.
ABS - U2023-A0 - Fault Received From External Node.
Air temperature - B1261-FF - Sun Load Sensor Short Circuit To Ground.

So i figured maby the battery in fact needed to be replaced. Took the car to the car parts shop, went in and got a battery and when i got out and started the car (stil with the old battery) all the lights where gone and the car ran fine!

Got home, changed the battery to the shiny (and expensive) new one. Started the car and took it for a ride and about 10 minutes into the drive the DPF started flashing, the check engine light came on and also the TCS/DCS. Pulled the codes and it gave the same result as above.

I have to use the car, have no option.. so I used it during the day. Then on my last drive yesterday once again the lights disappeared.
This morning i drove my kids to school and now the lights came on again.
I took the freeze frame data for the P0548 code, i will attach everything to the post. Perhaps someone with more knwoledge than me can make something out of it.

I would appreciate any advice! Normally i would just change the lambda sensor and be done with it, but since the TCS/DCS light comes on at the same time I get a bit baffles. Doesnt make any sence to me, those systems should be unrelated - right?

Any ways, long post, thank you for hanging on and like i said - i will update this post regularly with what i do and the results.

Cheers / Ola (sweHNTR)



Freezeframe data for the o2 sensor code

Freezeframe data for the o2 sensor code

Freezeframe data for the o2 sensor code

Freezeframe data for the o2 sensor code

 

My view is that the engine temp is low, this will cause it to over fuel which gives wrong readings for the lambda sensor, which would trigger the codes. Once knackered it is best to replace it then you will know it is not that, and put in a new thermostat at the same time as that could now be stuck open after the 'fluid' turned to jelly, along with a complete empty and refill of coolant. Just my opinion, but worth a try and reasonably cheap and easy to do.

 

Thanks alot for trying to help me!

Im almost positive i have found the problem now. Havent had time to fix and check yet.

But the other day i had the car parked and running. It was dark outside and I noticed quite alot of exhaust coming up from the front of the car. I havent removed the coverplates and checked but i would say the leak is before the DPF. Manifold perhaps.

I will fix and update the thread 😊

 

You're not gonna like this solution but...You're gonna have to move to a warmer climate!