SES light, no codes present

**RAMAIR_LS1** · 10-10-2009, 02:05 PM

Having a bad time with my '98 WS6. Was throwing code 0135 for bank 1 sensor 1 O2 sensor, replaced both front sensors, cleared the code with scan tool. Still getting a flashing SES. Scanner says no codes (or pending codes) detected. No mis-fires detected with scanner either. Flashing SES comes on from 25-55 MPH, also goes out at 30-25 MPH when slowing back down, never comes on in park at idle. Car has back 02 sensors deleted, long tube headers. TP sensor checks out fine. Professionally built with stage 2 heads/cam/ls6 intake back in 2001, low mile, dry weather only car. Can someone shed some light on my condition?

**SVG210** · 10-10-2009, 09:13 PM

when the SES Light flashes it means its detecting a misfire, check your plug boots, one of them might be loose.

**35th-ANV-SS** · 10-10-2009, 09:34 PM

Originally Posted by SVG210

when the SES Light flashes it means its detecting a misfire, check your plug boots, one of them might be loose.

Used to think the same thing.

blinking (S.E.S) light is a catalyst damage indicator not a misfire light . a class 3 (sever)misfire will cause this because of unburned fuel going through the cat's. but other things can also cause this (defective ect sensor )

FROST agrees with the above.

**RAMAIR_LS1** · 10-11-2009, 05:53 AM

I've been searching for several hours...plugs fine, can't find a loose connection or hear a misfire at any RPM.No burnt wiring. Has never been over-revved. It just started doing this when I was less than a mile from home on a short drive. Weather was (and is) around 30 degrees, factory baffles are removed from hood also. Car runs great, as it always did...light kicks off in neutral and/or drive as the car slows to 30-25 MPH. Forgot to mention no cats on the car. MAF is spotless, but I cleaned it as well last night.

**Frost** · 10-11-2009, 06:31 AM

If you only get it at cruise, it could easily be false reporting from the camshaft.

What did you do in the misfire section when you tuned your car? Those thresholds are likely too low.

**RAMAIR_LS1** · 10-11-2009, 07:28 AM

I didn't tune it myself, the car was dyno tuned by Agostinos after the modifications in 2001 and hasn't been touched since. I disconnected the battery last night, and just re-connected it, checked ECT incoming voltage at connector-4.99 volts. Any help you could give me would be greatly appreciated.