17-18 MPG on highway

**.melissa.** · 06-17-2008, 09:34 PM

My 2001 WS6 is only getting 17-18 mpg in 6th @ 1300 rpm on the highway. Does anyone know what could cause such bad gas mileage?

Also the check engine light was on and I had it tested and it said sect. 2 cat. convertor. Are these expensive to replace?

**0rion** · 06-17-2008, 09:58 PM

your cats are still under warranty. 00-02 warranty got extended to 10 years 120k miles. It was discussed some in this thread. cat sticky what was the actual code the car threw?

How many miles are on the car and how long since your last tune up? Any drivability issues with the car or is it just a gas mileage issue? Could be as simple as just needing a tune up.

**.melissa.** · 06-18-2008, 12:19 AM

Originally Posted by 0rion

your cats are still under warranty. 00-02 warranty got extended to 10 years 120k miles. It was discussed some in this thread. cat sticky what was the actual code the car threw?

How many miles are on the car and how long since your last tune up? Any drivability issues with the car or is it just a gas mileage issue? Could be as simple as just needing a tune up.

I am not sure the actually code. I am going today to get it checked out. Ive only had the car a week. I changed the oil 2 days ago and I am waiting on my dad to put the plugs in.

The car has 96,000 miles on it. The car drives great.

**JoshieDoom** · 06-18-2008, 01:00 AM

Probably clogged up cats.

A tune-up should wake the car up!

**qwk93ta** · 06-18-2008, 02:55 AM

I had my right side cat replaced by GM a few months ago in my 00 WS6.

**QKSLVR99** · 06-18-2008, 05:39 AM

yeah tune up def. recommended fuel filter, more than likey replace cats or just get rid of them all together

**astyles** · 06-18-2008, 06:07 AM

since my cats blew out i am getting tons better milage.....b4 it was crappy

**.melissa.** · 06-18-2008, 02:29 PM

Thanks. I will see whats up with the cats and hopfully just get rid of them. If I get rid of them will the check engine light stay on all the time or will it go off?

**Mr. Luos** · 06-18-2008, 02:49 PM

Originally Posted by .melissa.

Thanks. I will see whats up with the cats and hopfully just get rid of them. If I get rid of them will the check engine light stay on all the time or will it go off?

If you get rid of them, you will have to have the codes turned off via HPTuners, LS1Edit, or similiar software.

**astyles** · 06-18-2008, 06:12 PM

yea my check engine light has been on for awhile now.......

**JoshieDoom** · 06-19-2008, 09:22 PM

<---stares at the SES all the time...

**LgndKller20073** · 06-19-2008, 09:59 PM

My SES light just popped on today. had the code read; P1404. I'm just going to unplug the EGR valve harness, reset it, and plug it back in. Hopefully that fixes it. Having those lights on bugs me. I have to reset the change oil light immediately after it pops on.