problem started last night.. cel light, vsa came on, car cant go past 45mph.
took it to autozone this morning to get cel code checked and got P0721.. it says "problem in countershaft speed sensor circuit". i did some searching last night and found a few users having the same symptoms but with different codes. their problem was their accelerator pedal sensor.. my question is .. are the two related? is it the same problem?
i called my local ripoff dealer and asked them about the cel code and he said auotzone reads different code numbers than they do and that i should bring it in.. then they quoted me $120 just for a diagnostic..i just need to know if the problem i got is the same as the pedal sensor or something else i can buy myself and swap out....

 

any trans slipping? that will fool the computor into thinking an engine overrev has occured and goes into limp mode
Have you overreveed at any time? missed shift and thought it may have hit the redline?

or the crank speed/position sensor really is bad

service writers job is to get you in the door- get $120 out of you for diagnosis and another 200-500 for repairs--its a scam!!!!!

`they read different codes than autozone` hahahahahahaha
maybe on an ABS prob they have a special scanner~

 

people with different codes likely have different problem

 

nope no slippage... my wife was driving it last night when it happened.. when she got home i got in started it up and when i revved the engine it wouldnt go past 4500 rpms. it kept bouncing back and forth.. thats when i did a search here and found out about the app sensor problem.. i REALLY dont want to go to the stealership for this if i can fix it myself.

 

I'd also suspect at the Accelerator Pedal Position (APP) sensor first.

 

thats what im thinking .. but i need to know if the countershaft speed sensor is the same thing before i order anything...thats where im stuck at..

 

No, they're not the same. And usually, the APP sensor throws a P2138, IRRC...

Edit: In addition to P2138, the other codes for APP sensor (from the SM) are: P2122, P2123, P2127, P2128.

Did you get a flashing "D" at any time?

 

thanks for that bit of info... thats why i didnt order the app sensor yet, i wanted to make sure there was a difference... would you happen to know anything about the countershaft speed sensor? is this something i can order/buy and replaced myself or am i at the mercy of the dealer...

 

No, you can replace it yourself. I have no idea what it costs. You can talk to or PM one of the Azine Acura parts dealers and get a price. Use the "Vendors" link at the top of the page. Be sure to mention you're an AZine member.

A note from the SM says that this code is electrical in nature, not mechanical. Be advised, there is an extensive troubleshooting procedure in the SM. Replacing the part may or may not fix your problem. You may have a loose/bad connection at the PCM and/or the unit itself.....

Have you had any maintenance performed or any mods to the car?

Give me a minute and I'll post the SM scan for removing the part.

 

no mods.. car is stock.. no recent maintenence... i tried looking for that part online earlier, when i got the code read but could not find it... i already called pepboys and another autozone and they didnt have it either....i will keep looking.. if the fix is easy and inexpensive i may give it a go. if not then i may have to the dealer..
thanks for helping out.

 

That's what I thought too...But according to the SM, the HDS (Honda Diagnostic System) does indeed read a different code. For the output shaft speed sensor, it's "9-5".

 

PM Caleb at Peoria Acura...

Did you ever get a flashing "D" (in the Tach guage) ????

 

so this thing is under the battery and air filter housing? i just gotta make sure i have my radio codes before i unplug the battery.. im gonna look around for this piece asap.. this looks doable.. i just hope thats all it is.. last question.. once i swap it out and leave the neg terminal off for a bit, will the cel light go off, or will i have to go somewhere to get it reset? thanks again for your help.

 

never saw a flashing D.. gotta try and get this part locally and fix asap since this is the only ride we have... if not then i will pm caleb.

 

http://www.acurapartswarehouse.com/P...gPicture=False

part #15 in the diagram. Acura part #28810-PPW-013, $39 plus shipping....

I don't believe that disconnecting the battery will erase the P codes (stored in non-volatile memory), but if the PCM doesn't sense any problems after replacing the part, then you shouldn't get another CEL...

 

Missed this...Were you revving it while in "P"? If so, there is a rev limiter built into the PCM while in "P". I think it's set to cutout around 5K (while in "P"), so it's likely you were hitting the rev limiter....

 

thanks a ton nfn... i just got off the phone with sean at oemacuraparts.com and he mentioned the same thing about 9 pages of electrical diagnostics, and that swapping it out may or may not solve my problem... crap... looks like i gotta bring it to dealer anyway.
again thanks for all your help today.

 

Sure thing...Probably a wise decision. With labor rates at $100-$125/hour, $120 is not bad for that monster diagnostic procedure...

Report back and let us know what they tell you...

 

will do... would be sweet if whatever the problem is falls under warranty.. (not gonna hold my breath on that one)...

 

Im currently having the 'exact' same issue on an 06 TL. Even went as far as changing the Output Shaft Speed Sensor. Unfortunately that didn't work. I am curious if you found a resolution...

PS. This is my first post. Only wished it could have been under better circumstances

 

problem turned out to be my tranny. i brought it to the dealer last week and at that time with the cel code they also thought it was the speed sensor. they replaced it and i thought all was fine until my wife mentioned the car was slipping. so i took it out for some test drives and noticed the same thing. took it back on monday and they did find problems with the tranny. she just picked it up and says all is fine now.. pulling like a champ. i will do some test runs this weekend to make sure all is well. fyi this was all covered under warranty (thank god).