Emissions light is on
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Elder User
Joined: Apr 2003
Posts: 673
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From: Maryland
Emissions light is on
So I was poking around under the dash and found a connector unplugged, when I plugged it in the emissions light came on. The connector (3 wires?) plugs into something that looks like a relay. Now I know why it was unplugged!
What is this light telling me? The shop manual is real vague on this one.
Is this a timed service interval type of light (resetable?) or is it indicating a problem?
The truck failed the emissions test, so I checked the computer's codes and discovered that the O2 sensor had failed. I also replaced the EGR valve since it was blown. My emissions troubles are now over the truck passed with a "fast pass" so I guess my next move will be to reconnect the light harness. Just looking for some background info.
Thanks!
What is this light telling me? The shop manual is real vague on this one.
Is this a timed service interval type of light (resetable?) or is it indicating a problem?
The truck failed the emissions test, so I checked the computer's codes and discovered that the O2 sensor had failed. I also replaced the EGR valve since it was blown. My emissions troubles are now over the truck passed with a "fast pass" so I guess my next move will be to reconnect the light harness. Just looking for some background info.
Thanks!
New User
Joined: Jan 2008
Posts: 0
Likes: 24
Emissions light is on
Whoever replaced the O2 sensor should have cleared the codes or disconnected the battery for 1/2 hr to clear the codes.
The problem triggers the service light and stays on until the problem is fixed.
Apparently the P/O decided he would rather disconnect the light
The problem triggers the service light and stays on until the problem is fixed.
Apparently the P/O decided he would rather disconnect the light
Lead Driver
Joined: Oct 1999
Posts: 6,772
Likes: 551
From: Kalispell, MT
Emissions light is on
Years ago when my 86 hit 60K miles and the check engine light came on, I was told by a service manager that Ford programmed the 60K benchmark into the computer so that the entire emissions system could be checked and several parts replaced as necessary. Tech's were required by law to perform all tests before the computer could be cleared. General cost for this service back then was around $700.
I took the dash apart and removed the lightbulb. That was 250K miles ago.
I took the dash apart and removed the lightbulb. That was 250K miles ago.
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
Emissions light is on
There's a small module called the "Extended Useful Life/Inferred Mileage Sensor" in the dash, and that's probably what you found. It's "inferred" because before '87, there was nothing on the truck that electronically measured actual mileage, so I suspect it detects runtime. It might kick in at 10,000 mi on a vehicle that spent a lot of time at idle or in low range, or at 100,000 on one that was used for long highway trips.
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LCconvert
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Sep 27, 2015 07:56 AM
