I think we're all wrong about those cheap code readers

Had a 2012 Civic come in yesterday with a P0420, cat efficiency code. Kid had one of those $40 Bluetooth readers from the auto parts store and was sure he needed a whole new cat. I told him to hold up, let's check the basics first. Hooked up my real scan tool and watched the O2 sensor data. Upstream was lazy, barely moving. Threw a new sensor in, cleared the code, and sent him on his way for about $120 total. Everyone says those cheap readers are junk because they just give codes, but I think the problem is we expect them to do a pro's job. They're great for a quick check, but you can't skip the real diag work. How many of you have seen a simple sensor fix a 'cat' code that a customer diagnosed themselves?

3 comments

3 Comments

bailey.karen14d ago

You're right about expecting them to do a pro's job. I read a forum post once where a guy said those cheap readers are like a check engine light for your check engine light. They tell you something's wrong, but that's where their job ends. It's on you to figure out the real cause, just like you did with that O2 sensor.

calebw5014d ago

Honestly, that 2012 Civic story is a perfect example. I've seen the same thing maybe a dozen times where a P0420 was just a bad sensor. Ngl, I really like what @bailey.karen said about it being a check engine light for your check engine light. It's a good first step, but you still gotta do the real work with proper tools to see the live data.

taylor_fox7h ago

Totally, and that's why @calebw50 is spot on about needing the real tools. My buddy swapped his whole CAT for a P0420 before checking the data, and it was just a lazy downstream sensor the whole time. Live data doesn't lie.