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Ron
Ron, ASE Certified Technician
Category: Chevy
Satisfied Customers: 35291
Experience:  35 years experience with ASE Certs
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Ok, so here's what happened: my exhaust needed welding

Customer Question

hi there! ok, so here's what happened: my exhaust needed welding so a friend of mine did it and, in so doing, needed to disconnect the oxygen sensors. when he finished he forgot to reconnect them. about 3 days later the check engine light came on. when
i told him he remembered about the sensors and said hed reconnect them for me but never got around to it and i drove the car like that for approx 3 months. then i needed to get it smogged. so i enlisted the assistance of a different friend who first checked
the obdII codes, which ended up being: P0140 (O2 Sensor Circuit No Activity Detected Bank 1 Sensor 2) P0141 (O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 2) P0154 (HO2S Circuit Insufficient Activity Bank 2 Sensor 1) and second helped me reconnect the
sensors. i then drove around for about 3-4 days and the check engine light turned off. so i took it to get smogged. it passed everything except the "obd system checks". i was told to drive it some more (1 hour +*****each day for 3 consecutive days).
this is a lot of driving and in southern california expensive in gas but, ok, i did that. in another few days i went back to the smog place. when he checked with the obdII, he became very perplexed looking and baffled. he explained that those same 3 codes
came back up (as current, not history) yet the check engine light was not lit. he offered to clear the codes out, have me drive some more and come back to try again. in the meantime i decided to do a little research and learned that there is this thing called
a "drive cycle" and that i needed to take the vehicle through specific steps in order to get it to check each monitor of which there are 8 apparently. so armed with this new info, which also said a complete drive cycle could be completed in 15 minutes, i got
in the vehicle. very soon, i learned another thing which is how dang long it takes to decelerate from 55pmh to 20mph without touching the brake or the clutch. there was no location i found where that maneuver was possible. i then enlisted the help of one more
friend who showed me where a long street in an industrial area was where i could perform this maneuver. however, when we got there, there was much confusion about exactly how to perform this. for instance: (see attached file) does step 5 need to be performed
immediately after 4, meaning can i say drive on the fwy holding at 55mph for 3 minutes then slow down using the brake and clutch to exit the fwy drive to the specified street upon which i'd be able to decelerate then take it up to 55mph for a moment (but not
3 minutes) and decelerate? also- do i decelerate all the way to 20mph in gear, because it started feeling like it was going to stall before i got to 20mph? so do i get to 55mph in a lower gear or do i pop it into neutral without pressing the clutch? (that
is what i did, by the way, popped it into neutral without the clutch) anyway- you get the point. while i cant say it wasnt a really fun (and funny) little adventure, what i can say is i by the end of it i remained unconvinced i had performed each step properly.
i went back to the smog place today. 3 of the 8 still are not ready: catalyst monitor diagnostics, fuel evap, EGR and he also wrote 172 780 on the sticky note (he was NOT very forthcoming with info). assuming that refers to new codes that came up (although
he didnt mention that) those refer to: ***** ***** Too Rich (Bank 1) and Shift Malfunction, respectively. Sorry for the diatribe! Here's my question: This guy wants, now, a minimum of $200 to diagnose (not necessarily fix) the problem. In your expert opinion,
IS there a problem (versus i simply have not yet been successful in completing a drive cycle)? *sidenote: i also read that if the catalyst is marginal (whatever that means) or the battery has been disconnected it may take*****cycles to determine
the state of the catalyst* and last question: if there IS, in your expert opinion, a problem is that a reasonable amount to pay for a diagnosis? thank you in advance for your assistance!
Submitted: 1 year ago.
Category: Chevy
Expert:  Ron replied 1 year ago.

Hello, my name is ***** ***** I am a professional here at Just Answer. I have noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

The problem you are having is very likely as you suspect and getting the drive cycle to set can be a real pain in the rear especially if you do not have a clear area to do it. In order for it to complete you need to follow the drive cycle exactly as stated in the tests, starting the engine when temperature of the engine is below 122 degrees. I have enclosed the steps in the link below, if you have never done this you may want to consider getting someone who has to help you with it.

https://dl.dropboxusercontent.com/u/104923897/Drive%20cycle%20Sept%202.pdf

Copy and paste the link to your browser to open and view it.

https://dl.dropboxusercontent.com/u/104923897/Drive%20cycle%20Sept%202.pdf

Customer: replied 1 year ago.
Thank you for your help! Is there any validity to that thing I read about a situation where I'd have to complete the drive cycle 5 times? And, also, do you have any suggestions about what to do if I am unable to complete the drive cycle properly?
Customer: replied 1 year ago.
a couple of questions about performing the drive cycle:
1) so...there Is no need to hold it at 55 mph for three minutes before doing the first deceleration?
2) on the second deceleration is it not necessary to keep the clutch engaged?
Expert:  Ron replied 1 year ago.

Its not uncommon to have to do the cycle a few time before it will complete and if you follow the steps just as written it should complete.

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