FQ-300

iTrader: (17)

Coincidentally I had the same thing happen when I bought my new Evo VIII. Before I bought it, I ran a carfax (car had 269 miles at time of signing) and there was a blemish. Come to find out the cat was replaced (approx. 185 miles on the odometer) to the tune of $730 and some change. I thought it was a fluke, but sure enough I called the dealer for cat replacement cost and it was the same amount. Now who in their right mind would pay that much, beats the hell out of me...

zarl

Fortunately, the catalytic converter is covered under the 8 year/80,000 mile emissions warranty. So, this is no cost to the owner for the parts or labor for a long, long time.

kinloch99

the dealer makes alot more money changing the cat, answer solved...

zarl

Would you guys drive with the cat/sensor issue? The service engine light was reset by the dealer and it's not throwing a code at the moment. I'm thinking about leaving the car in the garage for a week until the new cat comes in. What do you think?

BABYEVO 8

iTrader: (2)

My 06 Eclipse had a recall that they replaced the Cat... could be a similar issue!
replaced under warranty

EvolvedVIII

iTrader: (7)

You won't have any problem driving with a faulty cat.

Turbolover

iTrader: (5)

who needs a stinkin cat

Tristar

iTrader: (7)

Im not exactly sure, so dont get mad if Im wrong, but maybe there is another cat before the primary one, maybe somewhere in the downpipe or elsewhere after the turbo?

I cant imagine a 4 hour service time for a cat thats under the car, but I could imagine it if it was near the turbo manifold and you had to remove alot of stuff to get to it.

Just a thought, again Im not saying this is the actual case....

LancerEVA06

iTrader: (3)

I had 25,000 miles on my '06.... MIL came on... took it to the dealer... needed a cat. Mitsu has this bright idea to run a cat without a air pump and run the cars rich..... they heat up too fast and too much and fail

hel_if_ino

iTrader: (2)

Correct me if I am wrong but, all new cars dump fuel on startup to rapidly heat up the cat, I can't see car manufacturers doing this if it would lead to a premature failure. Also, I would say this is a case of "**** happens," and I wouldn't worry about it, drive it in the meantime. Good luck

Blue Evo 8

iTrader: (40)

yes, 4 hours of labor...

1 hour to loosen each bolt....

EvoRecordSetter

i bet if they cleared the code it wouldnt come back.

PDXEvo

iTrader: (4)

Hrm, this could be anyone of several sensors causing this. In laymens terms, the code is related to the difference between the front and back o2 sensors are too close. Here is the full write up.

DTC P0420: Warm Up Catalyst Efficiency Below Threshold
TECHNICAL DESCRIPTION
• The signal from the heated oxygen sensor (rear)
differs from the heated oxygen sensor (front),
because the catalytic converter purifies exhaust
gas. When the catalytic converter has deterio-
rated, the signal from the heated oxygen sensor
(front) becomes similar to the heated oxygen
sensor (rear).
• The ECM compares the output of the heated oxy-
gen sensor (front and rear) signals.
.
DESCRIPTIONS OF MONITOR METHODS
Heated oxygen sensor (front and rear) rich/lean
switching frequencies are nearly equal.
.
MONITOR EXECUTION
Continuous
.
MONITOR EXECUTION CONDITIONS
(Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored
in memory for the item monitored below)
• Heated oxygen sensor (front) monitor
• Heated oxygen sensor (rear) monitor
• Heated oxygen sensor (front) heater monitor
• Heated oxygen sensor (rear) heater monitor
• Heated oxygen sensor (front) inactive monitor
• Heated oxygen sensor offset voltage monitor
• Misfire monitor
• Fuel system monitor
• Air/fuel ratio feedback monitor
Sensor (The sensor below is determined to be
normal)
• Mass airflow sensor
• Engine coolant temperature sensor
• Intake air temperature sensor
• Barometric pressure sensor
• Throttle position sensor
• Accelerator pedal position sensor

DIAGNOSIS
Required Special Tools:
• MB991958: Scan tool (M.U.T.-III Sub As
• MB991824: V.C.I.
• MB991827: USB Cable
• MB991910: Main Harness A
STEP 1. Replace the catalytic converter.
(1) Replace the catalytic converter.
(2) Carry out a test drive with the drive cycle
Diagnostic Function − OBD-II Drive Cycle
P.13A-9.
(3) Check the diagnostic trouble code (DTC
Q: Is DTC P0420 set?
YES : Replace the ECM. When the ECM
register the ID code. Refer to GRO
Registration Necessity Judgment T
with KOS> P.42B-12 or GROUP 4
Registration Judgment Table <Veh
P.42C-9.
NO : The inspection is complete.

AnimalEvo

iTrader: (1)

Did you pop the code at WOT or after a stint of romping on it? I know most cars with hi-flo cats installed will pop this code occasionally after a WOT where the car runs rich and tons of fuel is not being burnt. The extra unburnt fuel hitting the catylist pops the code.

zarl

Thanks PDXEvo for posting this.

Well, it appears that they're following the book by replacing the cat as Step 1, so that seems like the legit thing to do.

I've put another 40 miles on the car since they reset the code, and no code has popped up since then.

When it first came up, it was after driving the car for 2 miles or so first thing in the morning. Stopped for a cup of coffee, started up the car, and the light came on. No WOT or aggressive driving. I have been going really easy by the book for the break in. I'll report back next week after they replace the cat.