Catalytic converter or transmission?

Asked by Apr 04, 2015 at 07:44 AM about the 1998 Chevrolet Blazer LS 2-Door RWD

Question type: Maintenance & Repair

I have a 98 chevy blazer that started losing power a month ago on an incline. Up until then, the car ran great. The reading i got
from the auto store were egr sensor,  catalytic , and maybe 1 other. I replaced the egr, mass air flow, o2 sensor, spark plus and
wires, fuel filter, and pour in fuel cleaner. I sent it to a shop and explained that i was losing  acceleration on an incline, hoping that
they will diagnose the catalytic converter and replace it. To my surprise  they call me hours later and explained that the
transmission is going bad and it is not even shifting into first gear. But i haven't  experienced that problem or transmission
symptoms. They guy said the car is done and he does not recommend a new or old transmission. I need a second opinion. I was
hoping to replace the catalytic  converter.  It is had to believe  that it is the transmission without prior symptoms  or showing on
the diagnostic reading. Thanks

6 Answers


Have you noticed that the vehicle is not down shifting when going up hills? Have you manually tried shifting down into 3'rd when you feel a loss of power going up hill? I doubt it's the cat. You would notice a power loss at all times. Is it showing any error codes? Is the check engine light on?

1 of 1 people found this helpful.

Would need more info to really diagnose. Confirm what gear it's in and make sure your getting all 4. A common failure is the shift solenoid. Sometimes it will drop 1st and 4th gear. However you shouldn't be dropping all the way to 1st unless your trail riding or towing things you shouldnt. Clogged cats usually give a false redline and is noticeable on hills or flat ground.

I went to the auto shop today. The mechanic now say that it may be that Blazer's computer is bad and therefore it is not reading the o2 sensor, egr sensor, and signaling a bad transmission.

(apologies if this makes not senese) but Also to hopefully to answer the question. He said that it would not shift out of first gear. Well I asked the mechanic to drive it with me in the truck because I had not experienced it. During the drive it shifted into 1st gear immediately, then again at 3000 rpm. He was convince that the truck was done until I explained the above and the parts that i replaced as well. The truck would not pass emission due to readiness. I drove 150 miles and the same 3 (erg, o2 and catalytic converter) continue to show. He also ran the diagn. showed the same thing and a code if not mistaken, 4.0 or 4.4 (he checked with his laptop).

The check engine light is on.


First these guys think it's the cat then they're telling you the transmissions bad and to basically scrap the car. Now they're telling you it's the computer. I would bring it elsewhere. I think these guys are just fishing for a big bill. You will have to take it to a good shop to have it properly diagnosed. It could be the BCM or the PCM. When the mechanic says things like, "Well maybe it's this or maybe it's that." that's your clue to go elsewhere. They will be blindly replacing parts and you'll be footing the bill. And once they replace electrical parts, they usually won't give you your money back.

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