Transmission light still on?

2006 MAZDA 6
168,000 MILES • 2.3L • 4 CYL • 2WD • AUTOMATIC
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ALEXSCRUFF61
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Hi there,

I was driving up a hill AT (automatic transmission light) appeared on dash, then car slowly came to a stop and wouldn't move. Had it towed to a mechanic shop who told me radiator hose had burst. You need a new radiator and set of hoses which I had installed...Went to pick up car and 5 minutes into driving AT light and check engine light came on and car would not go past 3rd gear. So drove back to the shop, been a week, still waiting to hear...Any ideas...was wondering if it could be a shift solenoid or a transmission speed sensor ..Mechanic had told me also battery was hard to crank after waiting for the radiator to arrive which took 2 weeks.
Thanks
Jun 17, 2025 at 2:31 PM
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STRAILER
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Yes it can be either the shift solenoid or a transmission speed sensor, we need to run the codes because the car sounds like it is in limp mode. Here are two guides you can go over so we can see what's going on:

https://www.2carpros.com/articles/reduced-power-limp-mode

And this guide can help you get the codes:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please go over these guides and get back to us.
Jun 18, 2025 at 6:43 PM
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ALEXSCRUFF61
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Thank you for responding.
I really appreciate your expertise.
That was the first thing I asked when I returned to the shop was can you please check the codes to see why it is in limp mode.
He has done excellent work on my car a bunch of times, and I know he's always busy.
He told me when the radiator hose broke a bunch of transmission fluid came out. So, I picked up a bottle of Bars leaks high milage transmission repair to add when he refilled it, Ya don't think that has anything to do with anything.
Jun 18, 2025 at 10:15 PM
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STRAILER
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Yep, that can cause problems, also did he refill the transmission after the repair? The transmission must use Mazda M-V ATF (also known as Ford Mercon V). Let me know how it goes.
Jun 19, 2025 at 10:26 AM
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ALEXSCRUFF61
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Hi again...
Mechanic says my Mazda has 2 codes,
P0734 and P0751.
As for the transmission fluid he says all of the fluid had come out when the radiator hose broke so he had to put about 6-7 quarts of the right fluid back in. The Bars leak would have been one quart...
He is recommending I take it to AAMCO transmission shop
Thanks again for your help...
Jun 19, 2025 at 1:38 PM
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STRAILER
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Yep, the transmission could have gotten damaged when the fluid ran out of it.

P0734 - Gear 4 Incorrect Ratio
P0751 - Shift Solenoid A Performance or Stuck Off

I would say try a turbine shaft speed sensor, but I don't think it will help, sorry.
Jun 20, 2025 at 10:38 AM
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ALEXSCRUFF61
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Hi Ken
Just wanted to give you the final outcome....AAMCO said I needed a new transmission...They found me a used one with only 48000 miles on it so they did a swap for 2000 bucks...Car has been running great since it was installed (keeping my fingers crossed)
Just wanted to thank you again for all your help and advice
Take care
Alex
Jul 31, 2025 at 12:06 PM
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STRAILER
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Hi Alex,

Glad you could get it fixed, thanks for letting us know. Please use 2CarPros anytime we are here to help.

All the best, Ken
Jul 31, 2025 at 12:52 PM