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Obd Ii Not Ready? Failed Emission Test

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My father has a 2001 Silverado with a 4.8L in it. The truck runs great, after replacing the fuel pump, but he has failed the Emission test here in the Baton Rouge area. The guy told him his Emission system is "not ready." There is no CEL and Autozone doesn't read anything on their code scanner. Any ideas before i have him take it to a shop?

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14 answers to this question

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Clueless here, You have no SES light, but failed? I don't understand the part about "not ready". Does the truck have mod's or missing emissions equipment?

 

Something don't sound right :seeya:

 

And welcome to the site.

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Truck is stock. Fuel pump was bad and the fuel pressure would run the truck, but it cause issues when he tried to take off in traffic. Had a bunch of different codes at random times, from misfires, oxygen sensors, and knock sensors. I did some searches and found similar situations due to fuel pump. So we changed it about a year and a half ago and have had no problem since.

 

Brother-in-law's friend had a scanner that said not all on-board readiness checks passed when he plugged it in. Thats when we went to AZ to see if their's could tell us anything. I guess i need to go see him again and get the list of items that were not "ready" so i can provide more detail.

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Was the battery disconnected just before going for the test? The truck would need more than a few miles for everything to be good.

 

Mark

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I'll ask but as far as i know he hasn't had any reason to D/C the batt since we did the feul pump.

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Disconnecting the battery neg side for a few minutes will re-set all the codes. If any new ones appear, then you have something to work with.

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Does the Scanner work on the OBD port, or is there no reading at all?

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Was the battery disconnected just before going for the test? The truck would need more than a few miles for everything to be good.

 

Mark

you need XX number of drive/start cycles for the emissions to reset to ready. i would guess the battery was disconnected when the pump was changed. if you drive it every day, it should reset in about 3-5 days of sooner..

 

good luck

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That sucks that they would fail your vehicle for OBD connection issues. That's just wrong.

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Yep - MA does this too. If all the monitors have not run & you try to get a sticker, you fail. In other words, if you try to clear a code to shut off the check engine light before you go to the inspection station thinking you'll get a sticker, it's not gonna happen. Their computer will say right on it "systems not ready".

 

There is a completely impractical drive cycle procedure that you can do to get the monitors running in about 15 minutes .... but unless you live in Phoenix, AZ on one of their many long, dead straight roads ... or have dyno access ... it'll never happen. You have to do a combination of city & highway driving over a few days to get them to run otherwise.

 

Another fine side effect of treehuggers getting their way in government ... :thumbs:

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I've got something similar going on.

I had a battery to give up the ghost. Came out and found it at 5.3 volts.

It left the computer in a confused state. Did goofy things like turning on the fans and leaving them on when the engine was turned off, etc. (Manual says they'll turn off after 3 minutes. Didn't happen.)

I disconnected the battery and let everything discharge overnight. Reconnected it and had no more symptoms.

I drove it for nearly 300 miles (several trips to work and home, plus around town errands) and my scan tool still shows "Readiness Monitor=N"

 

WTH? Is it supposed to take that long? My Trailblazer is "ready" after a trip to the store and back.

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It takes some drive cycles for sure to get the diags all to complete. My 98 Yukon took a few days, several trips, 150-200 miles total, city and highway. I had the laptop hooked up and checked the status and when it finally completed, took it to emissions where it passed just fine.

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Hi guys, new to the site. My 04 Yukon has the same issue with the "not ready to be tested" fail for emissions in MA.

I have driven close to 200 miles over the course of a week, mostly city driving. Does the combined highway and city

driving really make the difference for the computer to reset? When I went back to retest after having the evap-valve

for the gas tank replaced, this is what happened.

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If the EVAP Service bay test is NOT available, it may take up to 6 drive cycles, with up to 17 hours between drive cycles, for the EVAP I/M System Status indicator to transition to YES. Now with that being said are you sure the evap-valve cause the problem?

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When my inspection sticker was up in October it failed for "not ready to be tested" but I had no previous work done in over a year. There was a sporadic check light

that I figured was the gas cap (had it checked when this happened before), which I had replaced. No check engine light at time of original inspection, so I was aggrivated

of course that i failed for no apparent reason. Since the fall and into January it became very difficult to fill the gas tank; you could tell it wasn't venting correctly by the hissing and smell. I finally got around to fixing the problem which was a frozen vent soleniod. The shop checked for codes and it showed no codes found, so we figured this is was the

issue. They told me to drive 100-125 miles/ 5 days or so of driving for the computer to reset, but after 200+miles still not ready. I hate having the big "R" on my sticker! By the way the connection at the inspection computer showed "good connection".

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