Car

Ask a mechanic online and get answers to your car questions

Ask an Expert,
Get an Answer ASAP!

Code P0420. Code returns after clearing, changing octane,

Customer Question
Second opinion] Code P0420...

Second opinion] Code P0420. Code returns after clearing, changing octane, spark plugs. The spark plugs removed looked perfect. Is there a software update that will remedy this? The car is running great but no cruise, all wheel drive, abs, etc.

Mechanic's Assistant: How many miles are on the car? When did you last change the plugs?

60,000. Today.

Mechanic's Assistant: What is the model of your '60 Subaru?

2012 outback

Mechanic's Assistant: Are you fixing your Outback yourself? What have you tried so far?

Yes, I�m a mechanic. What I stated above. There�s no wave showing on the catalytic converter but no burn going on.

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

I replaced the engine due to down cylinder last summer, but this just started 2 weeks ago.

Submitted: 2 months ago.Category: Car
Show More
Show Less
Ask Your Own Car Question
Answered in 1 hour by:
5/28/2018
Auto Mechanic: john aka eauto, The Car Guy replied 2 months ago
john  aka eauto
john aka eauto, The Car Guy
Category: Car
Satisfied Customers: 17,485
Experience: ase tech
Verified

have you called subaru? they have extended coverage on many years for catylitic converters?

Ask Your Own Car Question
Auto Mechanic: john aka eauto, The Car Guy replied 2 months ago

?

Ask Your Own Car Question
Was this answer helpful?

How JustAnswer works

step-image
Describe your issueThe assistant will guide you
step-image
Chat 1:1 with an auto mechanicLicensed Experts are available 24/7
step-image
100% satisfaction guaranteeGet all the answers you need
Ask Chris (aka-Moose) Your Own Question
Chris (aka-Moose)
Chris (aka-Moose)
Chris (aka-Moose), Technician
Category: Car
Satisfied Customers: 1,330
1,330 Satisfied Customers
Experience: 16 years of experience

Chris (aka-Moose) is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry.

Stephanie PElm City, NC

used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future.

David L.Richmond, TX

9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much.

PhilMarysville, CA

Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible.

CharlesWalnut Creek, CA

As a single woman, I really appreciate an excellent and affordable opinion.
Thank you Geordie, I will not hesitate to contact justanswer in the future!

SueCharleston, WV

Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff.

JimCastleberry, FL

Excellent reply, and also very quick. Really sounds like the Expert knows what he is talking about. I will be back to use your service when I need more help with my RV.

DutchUSA

< Previous | Next >

Meet the Experts:

Chris (aka-Moose)

Chris (aka-Moose)

Technician

1,330 satisfied customers

16 years of experience

Ted G.

Ted G.

ASE Certified Technician

1,754 satisfied customers

20 years auto repair experience, ASE Master Tech, Mechanical Failure consultant, Expert Witness

George H.

George H.

ASE Certified Technician

1,564 satisfied customers

ASE Master Tech 15+ yrs, AAS Automotive Technology, Factory trained Asian specialist

GM Tech (Cam)

GM Tech (Cam)

Auto Service Tech

680 satisfied customers

GM Grand Master Technician 2007. 14 years experience.

Amedee

Amedee

Former ASE Master Tech

2,562 satisfied customers

ASE certified tech advanced level specialist. Wisconsin certified emissions state inspector

Jerry

Jerry

Master Mechanic

2,181 satisfied customers

ASE master, 30+ years. All makes and models. Trouble shooter, shop forman, service manager

Richard

Richard

ASE Certified Technician

1,009 satisfied customers

12 years Ford Lincoln/Mercury Jaguar dealership as a technician and shop foreman reparing all makes

< Previous | Next >

Related Car Questions
Code P0420. Code returns after clearing, changing octane,
Code P0420. Code returns after clearing, changing octane, spark plugs. The spark plugs removed looked perfect. Is there a software update that will remedy this? The car is running great but no cruise,… read more
Eric
Eric
Retired
N/A
14,436 satisfied customers
2012 kia soul. Problem cel P2096 (lean fuel mixture in post
2012 kia soul. Problem cel P2096 (lean fuel mixture in post cat 02 sensor. I have checked intake air tube. I replaced because it looked like a small crack where the resonator is connected. … read more
Barry Sergeant
Barry Sergeant
25 satisfied customers
I have an 2004 isuzu rodeo 3.5 v6 with 57,000 original miles
I have an 2004 isuzu rodeo 3.5 v6 with 57,000 original miles and while driving on a trip recently I activated the cruise and check engine light came on and set a po420 code, I went to the local parts … read more
Ironmike
Ironmike
ASE Master L1 performance ,Ford tech
Vocational, Technical or Trade Scho
1,773 satisfied customers
4 trouble code went on in the last week after a snow fall
I have 4 trouble code that went on in the last week after traveling on a snow and slushey road. The first code was P0410 and today I got B1238, C1245 and a P0302, The engine started running rough and … read more
Alex M
Alex M
Automotive Technician
Diplom
858 satisfied customers
2006 Scion XB: O2..Toyota OEM part..emissions..catalytic converter
I have a 2006 Scion XB that has been faulting a code P0420 for a while. Changed both O2 sensors(front one is Toyota OEM part, rear is Bosch OEM type with OEM conncetor)) out along with a brand new Cal… read more
Eric
Eric
Retired
N/A
14,436 satisfied customers
Suzuki Forenza: MIL..P0420..catalytic converter..as did the o2 sensor
my suzuki Forenza failed the state emissions test, because the MIL commanded-on light failed. the code given was P0420. I brought a new o2 sensor and the catalytic converter passes as did the o2 senso… read more
gemmechanic
gemmechanic
Diesel Teacher
Vocational, Technical or Trade Scho
130 satisfied customers
2005 Buick: p300, P0404, P0405, P0420..exhaust system..fixes
2005 Buick Terraza - P0300, P0404, P0405, P0420 - Engine light on. Sound like these refer to something in the exhaust system. Any typical or simple fixes?… read more
goodwrench9124
goodwrench9124
Lead Tech/ Shop Leader
Vocational, Technical or Trade Scho
2,571 satisfied customers
99 chevy suburban: tune..new wires, plugs, rotor, and cap...Hesitates
99 chevy suburban, 200000 miles. check engine light on po300, po420 & po430 just had a tune up of new wires, plugs, rotor, and cap and the po300 went away clear the codes and only po420 and 430 came o… read more
Tim West
Tim West
Service Manager
Computer/ Automotive certifications
16 satisfied customers
98 olds intrigue: it hesitates..steady..smoke out of the tailpipe
I have a 98 olds intregue and it is throwing a 420 and442 twice. My car runs great but it hesitates sometimes when i go to excellerate or even at a steady drive it will start to like chug i guess you … read more
Paul M ASE Master
Paul M ASE Master
Automotive College
3,307 satisfied customers
02 tacoma 4x4 3.4 V6 coding P0420. Code reader/eraser cleared
02 tacoma 4x4 3.4 V6 coding P0420. Code reader/eraser cleared but comes back. Resistance checks of A/F and 02 sensors within spec. No apparent exhaust leaks. Cat converter going south?… read more
Auto Go
Auto Go
Shop Owner
Associate Degree
590 satisfied customers
Ion 3: a bunch of searching, nothing quite matches
04 Ion 3 92k miles. Brand new to site. did a bunch of searching, nothing quite matches. codes p0300, p0420, p1599, p0565, p1584. Hard/no start. extremely rich exhaust. replaced plugs 8k ago with Bosch… read more
George H.
George H.
ASE Certified Technician
Associate Degree
1,564 satisfied customers
2005 buick: catalyst efficiencey below threshold bank..3.8 liter..eng
i recieved a code p0420 "catalyst efficiencey below threshold bank 1" what does this mean? my car is a 2005 buick lacross 3.8 liter six cylender eng.… read more
Glenn
Glenn
Technician/Trainer
Vocational, Technical or Trade Scho
392 satisfied customers
F-150: 3 obd codes, P0171, P0385, and P0420..spark plugs
My ''96 F-150 is getting 3 obd codes, P0171, P0385, and P0420. I''ve recently had the catalytic converters replaced and I''ve replaced the spark plugs. Can you help me interpret these codes?… read more
Amedee
Amedee
Former ASE Master Tech
Vocational, Technical or Trade Scho
2,562 satisfied customers
Saturn VUE: recall..mpg..a drop of power and check engine light came
I have a Saturn VUE which recently had an ignition module replaced as part of a factory recall. My gas milage immediately dropped from 26mpg to 21 mpg. I then experienced a drop of power and "check en… read more
goodwrench9124
goodwrench9124
Lead Tech/ Shop Leader
Vocational, Technical or Trade Scho
2,571 satisfied customers
2001 pontiac Grand Prix 3.1 V6 - i get the diagnostic
2001 pontiac Grand Prix 3.1 V6 - i get the diagnostic code P0420 - the catalytic converter was replaced 6 months ago and my check engine light is still on. Any suggestions what my next step should be?… read more
RussMasterTech
RussMasterTech
GM Service Technician
3 Years College
546 satisfied customers
The check engine light comes..cruise control..catalytic converter
The check engine light comes on, the cruise control stops working and the cruise control light flashes on and off. I''m told that it has to do with the catalytic converter. Makes no sense to me.… read more
Cummins Power
Cummins Power
RV Service Tech
Vocational, Technical or Trade Scho
30 satisfied customers
1997 Plymouth Neon service engine soon light on. 1st OBD ...
1997 Plymouth Neon service engine soon light on. 1st OBD test mechanic said misfire, replace plugs and plug wires. Three weeks later light comes on again. 2nd OBD test at dealer said misfire and PCV v… read more
Derrick
Derrick
Associate Degree
920 satisfied customers
2002 Subaru Outback: Legacy..trip..the check engine light came on
My 2002 Subaru Outback Legacy has 125K miles. All was well until the end of last summer when we were returning from a kayaking trip. About 5 miles from our house, loaded with my family and 2 tandem ka… read more
Auto Tech Guy
Auto Tech Guy
Associate Degree
196 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x