# 2009 Sentra 5 error codes



## bumpkinboy (May 22, 2014)

I have some very confusing (to me) issues with this car. 

After 1 hour of high speed (65mph) driving, car engine slows itself down to about 40 mph and stays there. If I turn it off for a while, it will run ok until it gets too hot again, then the speed drops again. 

First visit to dealer - they didn't find _anything _wrong and had no clue as to what was happening. On second visit, dealership diagnostics showed:
P0725 – engine speed sensor
P0726 – engine speed circuit range
P0841 – transmission fluid pressure sensor
P1778 – transmission reverse I/P circuit malfunction, OR step motor function
P0717 – system too lean (oxygen sensor?)

They wanted $7,100 to fix the car – replacing everything from transmission to catalytic converter. I don’t trust them, because they admit that they really don’t know what the basic problem is. They’re just going by the codes. I’d like to go about this repair in an orderly sequence, rather than just swap the transmission out, because I’d like to solve the basic cause of the issue if possible.

Manual says that computer brain will slow car down if transmission fluid gets too hot. I’m thinking that might be the problem. Car now does it’s ‘thing’ after 15-30 minutes of driving, and at lower speeds. Replaced transmission fluid, still does it. Transmission now does occasional hard shifting too – almost a banging.

I don’t know if the tx fluid really IS hot, or a sensor is bad, or the brain is bad. Or – the transmission itself is kaput. I’m prone to think that the fluid really IS hot, because of the harsh shifting, but I’m no mechanic by a long shot. The shifting issue tells me that there really is something ‘physical’ going on – not just a faulty sensor or computer chip. 

I was thinking of starting by replacing the radiator/transmission cooler completely, as the least expensive ($300 total) option. If that doesn’t solve the problem, then replace the transmission. Groan.

Anyone out there have any similar problem? Or - what would you do in this situation? I mean, what would you check out or repair in sequence to try to figure out what’s happening? 

Thanks!


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## rogoman (Dec 16, 2004)

It seems like all the trouble codes point to the transmission. The A/T in your car is a CVT. If your car is still under warranty, the existing powertrain warranty coverage of 5 years/60,000 miles was extended at no cost for CVT repairs, replacements or related towing, to 10 years/120,000 miles, whichever comes first.


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