G_Body_Man Dork
Nov. 8, 2015 5:01 p.m.

Whelp, I got a code reader, and I've finally narrowed it down to two things it could possibly be. The cat, or an O2 sensor. Part of me is leaning towards the cat being bad, mainly because all the O2 sensors are fluctuating. That being said, it could be a rogue O2 sensor that's messing with my readings. What do you think the problem is?

t25torx Dork
Nov. 8, 2015 5:41 p.m.

I would try a bottle of Seafoam and some some fuel system cleaner first. Cheaper than both other options.

pointofdeparture PowerDork
Nov. 8, 2015 5:47 p.m.

I've never had a catalyst-related code persist after replacing all the sensors at once (upstream & downstream). YMMV.

Kenny_McCormic UltimaDork
Nov. 8, 2015 5:49 p.m.

Downstream O2 codes can also be caused by bad connections, often the connector is under the car.

How many miles are on it? Sensors only last 100-150k miles before they start going out of tolerance and reporting lean, causing the car to run a little rich. Not sure if that will trip that code though.

G_Body_Man Dork
Nov. 8, 2015 5:58 p.m.

180,000 miles. Since the code pertains to bank 1, I'm assuming the catalyst has failed. Bank 1 reads in the 500s while Bank 2 reads in the 400s (whatever that means). Could the O2 sensors fallen out of tolerance?

Kenny_McCormic UltimaDork
Nov. 8, 2015 6:14 p.m.

At that mileage, shotgunning it with OEM (probably NTK, check rockauto) O2 sensors wouldn't be a bad start. If you have live data capability, look at the long term trims (LTT) values when running, more than +4-5%(i.e. trimmed 5% richer than baseline) and the upstreams are definitely shot. It will get better gas mileage with new ones if the upstreams have gone lean.

Ignition system tuneup isn't a bad start either.

What car are we dealing with here? Best to note that, talking in engines codes is poor form unless it's some sort of hot rod.

G_Body_Man Dork
Nov. 8, 2015 6:27 p.m.

In reply to Kenny_McCormic:

2006 Toyota Sienna FWD. I'll check the LTT values.

You'll need to log in to post.

Also on Grassroots Motorsports

Follow Us to the Nürburgring

1 day ago in News

Follow along as James Clay from BimmerWorld contests his first ADAC Zurich 24-Hour race at the Nürburgring.

Shark Bite: Back in 1997, Hyundai Was Into Rally

1 day ago in Articles

A Hyundai Tiburon as a rally car?

You Need This: Mazda RX-7 Turbo II Roller

1 day ago in News

What would you do with an empty RX-7 tub?

From the GRM Vault: Our First Drive of the Original BMW M3

2 days ago in Articles

We tested BMW's E30-chassis M3 back in 1989. Here's what we thought.

Great Moments in $2000 Challenge History: Minor Gasser

2 days ago in Articles

Here's what happens when you put a Chevy 350 in a Morris Minor.

What’s the Soonest That You Have Raced Your New Purchase?

2 days ago in News

This BMW M3 was wearing numbers 24 hours after getting registered.

You Need This: 2005 Lotus Elise

3 days ago in News

A Lotus Elise looks so right in British Racing Green.

2017 Mazda MX-5 RF

3 days ago in New Car Reviews

We're big fans of the Mazda MX-5. Now Mazda went and put a retractable fastback on their fourth-generation car. So, ...

Project Ramp Truck: Installing Sound Deadening

3 days ago in Project Cars

Time to cut down on heat and road noise making its way into the cab.

Eric Foss Sets Fastest Time Ever at the Tire Rack Ultimate Track Car Challenge

4 days ago in News

47 of the country's fastest cars battled it out for track supremacy.

Who Wants to Design the Next GRM T-Shirt?

4 days ago in News

Blipshift is involved, so you know that it will be cool.

Reader's Ride of the Week: Improving Upon the Ultimate Driving Machine

4 days ago in News

This E36-chassis M3 just keeps getting better.

OUR SPONSORS

Grassroots Motorsports Magazine

Subscribe Today

Also get your instant access to the digital edition of Grassroots Motorsports Magazine!

Learn More
nk3HdUC79AV9GkuvBH0rV0GlstpmSLqu