18 Air Repair OBDII Review Volume 2 Number 1
Five-Time Reject–A Case Study
From the September 2005 issue of Air Repair.
By Noah Zafrir, Owner; Factory Muffler Complete Auto
A five-time reject (year, make & model not important) for
monitors came into my shop after originally failing for
several codes including a CAT code (codes present:
P0102, P0152, P0300 & P0420). The previous repair
facility, which will remain nameless, replaced the PCM
with a rebuilt, replaced the O2 sensor and replaced the
catalyst. But the shop gave up after several attempts to
set the monitors and in particular, the CAT monitor.
Several months and a few thousand miles later, a frus-trated
consumer started experiencing other problems –
would not start on humid or rainy days.
Finally, the wise consumer used the book and chose
my shop. He made the
30-mile trip to my shop. I asked him to bring the
receipts from the other shop to know what had been done
to “try” to get this vehicle through the test. I also con-firmed
that the CAT monitor had not set to ready.
After reviewing the previous shop’s receipts and
reviewing their work, I replaced the O2 sensor with the
correct one called for, but I also experienced the no start
condition. I replaced the computer with a new one and
the harness to the coils and the problem disappeared. So
now I could finally find out what had to be done to set
the CAT monitor. My concern was that after several
months, more mileage and installation of the wrong parts,
the CAT might have been contaminated. The only alterna-tive
was to replace the four-month-old CAT under
warranty with a new one. The CAT monitor set to ready
within 20 minutes.
The moral of this story is: The consumer should have
used a shop from the book on the initial failure. It is not
to say that a shop that isn’t in the book can’t fix the
OBDII failure/reject, but because of my volume of OBDII
repairs, I have experienced a huge number of rejects for
CAT monitors not setting. Experience has given me the
ability to quickly diagnose and repair OBDII failures/
rejects efficiently saving money for my customers and
making my shop profitable.
How Important is Wiring
From the July 2005 issue of Air Repair.
By Pat Weber, Owner, Weber Automotive, Glenview, IL
A frustrated customer came into my shop with an OBDII
fail because of no communication. Another shop had been
unable to get it to communicate. Because I had little repair
history on this vehicle, a 1996 Jeep, I asked the customer
for a history. He did inform me that the vehicle had been
in an accident. He had very little problems with the
vehicle and it was well-maintained. I’m glad I found out
the vehicle had been in an accident as I wouldn’t have
even suspected it. The body job was one of the best I
have ever seen, and I probably wouldn’t have thought to
look for other damage that could have an effect on an
Upon further investigation, I found that the body
shop missed a few important items such as missing
ground connections and wiring harness damage. So I
spent a few hours fixing damaged and ungrounded
The result was we got the vehicle to pass the test
after another repair facility was unable to find the prob-lems.
The lesson learned from this experience is that
spending time with the customer to get a history of the
vehicle can give clues as to how to go about approaching
the problem. Knowing that the vehicle had been in an
accident, we checked for ground and power, which are
needed to establish communication. As OBDII vehicles
age, accidents and a vehicle’s wiring will be areas that
Damaged wiring affecting 1996 Jeep OBDII test. will need to be checked more thoroughly.
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