Check engine light on no codes

Tiny
JON2834864
  • MEMBER
  • 2002 HONDA CIVIC
  • 1.7L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 165,000 MILES
The check engine light is on but the code reader reads there are no codes. I have been told that it might be a transmission code. The engine runs fine the transmission shifts. All the fluid's are were they are suppose to be on the dipsticks.
Tuesday, August 22nd, 2017 AT 7:25 PM

3 Replies

Tiny
STEVE W.
  • MECHANIC
  • 14,766 POSTS
The CEL can come on for a myriad of codes. There are different codes for the power-train, body, HVAC, transmission, air bags, traction control, entertainment and more.
Most code readers only handle the generic P codes for the power-train and cannot read the others. Also, some of the readers do not work well on various imports depending on when/where they were built.

In your case you need a higher level scan tool or a dealer tool to read the codes. What code scanner do you have?
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Wednesday, May 19th, 2021 AT 1:44 PM
Tiny
JON2834864
  • MEMBER
  • 6 POSTS
I went to Autozone they had a cheap OBD II reader. And O'Reily's had a Bosch reader the SRS threw a code but the O'Reily's guy would not give it to me. I have been working on the engine and it is not showing any codes now. But the check engine light is still on. The SRS and ABS are on as well, but the check engine light flashes occasionally when going down the road. The Autozone person said that when there is not code that it is usually a transmission code. The Honda runs well. Could it be the viscosity of the transmission fluid? Would this scan tool work better: OBD2 scanner, Topdon ABS/SRS Scanner Universal CAN OBD2 Scanner OBDII Car Computer Diagnostic Tool Car Code Reader for DIY and Professional( Topdon Elite)?
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Wednesday, May 19th, 2021 AT 1:44 PM
Tiny
STEVE W.
  • MECHANIC
  • 14,766 POSTS
Usually a flashing CEL is a misfire. SRS and ABS will have their own codes that most of the low end units cant read. A CEL with no code is 99% of the time a result of a scan tool that cannot read that particular code. It could be a manufacturers specific code or transmission related. Without knowing the code I would not even guess at what it is.

I have seen reviews on the Topdon unit and it does seem to do better than the bare bones code readers. But I have never used on myself so I cannot say yes/no. I would find the manual for it and see what it covers on an 2002 Honda.
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Wednesday, May 19th, 2021 AT 1:44 PM

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