United States
Environmental Protection
Agency
Office of Air and Radiation
6401
April 1997
EPA#420-F-97-OD6
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Correcting Your
Vehicle s Emission
Problems
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By bringing your vehicle in for emission
testing, you have actively contributed to a
nationwide effort to help rid our air of
harmful pollution. Because these pollutants are
invisible, emission testing is the only way to find
out if your vehicle is part of the problem.
If you received this brochure, it means your
vehicle didn't pass the emission test. Don't worry,
you are not alone. About 20% of cars and trucks
don't pass the test the first time, because they
have high emissions or other problems.
This brochure explains the testing process you
just went through and provides helpful tips for
how to have your vehicle repaired so it will pass
the retest More importantly, the brochure
explains how you benefit from helping reduce
the' #1 cause of air pollution in our country —
vehicle emissions.
What's In It For You?
- High emission levels are a sign that your engine is not
performing the way it was designed. Poor engine per-
formance can mean poor fuel efficiency and it can even
cause major driving problems over time. This early
warning is an opportunity to find and correct problems
before they become more serious and cosdy.
By repairing diese problems, you probably will improve
your vehicle's fuel efficiency by 6% to 13%. This could
mean a savings of $40 to $90 per vehicle every year.
At the same time, you are preventing harmful gases
from escaping into the air we breathe.
What Was Tested
- The enhanced inspection and maintenance (I/M) test
performed on your vehicle checked the gases your
exhaust system releases and diagnosed how well the
entire system is working. It compared your actual
emissions to the allowable standards, which are based
on your vehicle model year and type. (By the way, you
are not expected to maintain your car as if it were new.
The emission standards are set to account for the car's
normal aging process.)
Specifically, the technicians measured your vehicle's
tailpipe emissions, checked the evaporative emission
control system, and inspected the on-board diagnostic
(OBD) computer, which monitors emission-related
components. A vehicle must pass all these I/M tests.
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-| Why Didn't My Vehicle Pass?
->-A vehicles overall performance can decline due to age,
use and inadequate maintenance. So, the vehicle will
release higher levels of dangerous pollutants including
carbon monoxide (CO), hydrocarbons (HC) or nitro-
gen oxides (NOx).
The testing center gave you a test report about your
cars performance during the test. This information is
crucial in accurately diagnosing the problem. Be sure
to take it with you when you go to the repair shop.
There are a number of possible reasons your emissions
are too high — and a professional repair technician can
diagnose and easily fix most of them.
A computerized vehicle does not need a traditional
"tune-up" because modern vehicles do not have
carburetors and ignition points. Problems commonly
occur in the oxygen sensor and other sensors, the
catalytic converter, the fuel injectors or carburetors or
other emission controls. However, replacing a catalytic
converter should be the repair of last resort, unless it is
missing or has been tampered with. If you do need this,
be sure the new catalytic converter is the correct type for
your vehicle and is from a certified manufacturer.
What You Can Do
••>- Call in a professional
Do not attempt to diagnose or repair the problem your-
self. Only an expert repair technician, trained in diag-
nosing and repairing modern, computer-controlled
vehicles should service your car.
Look for experience, training and certification. If you
do not have an established relationship with a repair
shop that does advanced engine performance diagnosis
and repair, check with the emission test station.
It will have a "report card" for each repair shop in your
area, showing the percent of vehicles that passed the
retest after being repaired at that shop. Your local con-
sumer protection organization may also be a source of
information on a repair shop's record.
Check the vehicle warranty —
You may still be covered
Even if you think your warranty has expired, your emis-
sion repairs may still be covered. The law requires vehi-
cle manufacturers to provide a separate warranty for
vehicle emission controls.
Your owners manual tells you which parts of your
vehicle the warranty covers and for how long. If your
vehicle is covered by one of the following warranties,
you may be entided to have repairs done free of charge,
at die dealership:
>-The Emission Performance Warranty covers
any problem that would cause a vehicle to fail an
enhanced emission test (if the vehicle has been prop-
erly maintained) for two years or 24,000 miles.
XThe Emission Defect Warranty covers major
emission control components on 1994 and older
vehicles for five years or 50,000 miles. Beginning
with 1995 models, this warranty covers the catalytic
converter, oxygen sensor and on-board diagnostic
device for eight years or 80,000 miles; all other pri-
mary emission control devices are covered for two
years or 24,000 miles.
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If any covered components fail during die warranty peri-
od, the manufacturer must repair or replace them for free.
Visit or call die repair shop to find out if it is the best
one to diagnose and repair your vehicle. Some ques-
tions you should keep in mind:
>-Does the shop routinely handle the make of vehicle
you have?
>"Do diey clearly post or explain all policies (labor
rates, guarantees, methods of payment, etc.)?
>-Will the shop warranty the diagnosis and repair of
your vehicle?
XDoes die repair shop have modern diagnostic equip-
ment in the service bays?
>-Are the shop and technicians certified by the state or
a nationally recognized certification organization
such as die National Institute for Automotive Service
Excellence (ASE)? Is the certification related to
engine and emission repairs?
Work with the technician
To correcdy diagnose the problem, it is important to
provide as much information as you can to the repair
technician. Be sure to take die test report you received
at the time of inspection to the repair shop; it contains
detailed information that is valuable to die technician
in diagnosing the problem.
A good diagnosis might take some time. It should
include a thorough inspection of the emission control
system and detailed engine performance control checks
using sophisticated electronic equipment. It is worth-
while to invest some money for a proper diagnosis to
pinpoint the problem and avoid guesswork and unnec-
essary repair costs.
y :• /'•-Here's' a helpful checklist when
'( working with your repair shop:
/ Ask for an estimate on the cost of diagnosis up
• ••'•'.;.. front. ;-.- , • ' .,.::-". ,./,,:•'1'.; '•'.'•
- •/ Once your technician has identified the problem,
'{'- , ask about various repair options. If you are unsure
about the diagnosis, you can always get a second
|»r f 'opinion.
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Ti / Get a written estimate and description of the
*- repairs to be performed.
•/ Ask the technician to contact you for approval if
any work not included in the original estimate is
to be done or if the cost will exceed the estimate
by more than 10%. .
t / Keep a copy of any authorization forms you sign,
with all repairs listed. V" • :•••'
'f / If parts are replaced, ask to see the old parts and,
JH^ if possible, have them show you the defect
/ When the repairs are complete, be sure to have
the technician fill out and sign the repair
portion of the test report provided by the
test station. The form is on the back of the test
report and must be completed by the repair shop
before you can get retested. ; ••-•••.••.
Retest your vehicle
Once your vehicle has been repaired by a professional
technician, return widi the signed test report to the
emission tesrcenter to have your vehicle retested. If the
repairs were successful, your vehicle will run cleaner than
the allowable standards. As a reward for your repair
efforts, you can enjoy better gas mileage (an average of
6% to 13% better) and longer use of your vehicle.
Enhanced emission testing serves as a double-check diat
the emission control system is working properly and
you are getting peak performance from your vehicle.
By taking an active role in keeping your vehicle main-
tained, you are doing your part to reduce pollution and
make the air we breadie safer for everyone.
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