How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask GMTechBernard Your Own Question
GMTechBernard, Shop Foreman - GM World Class Tech
Category: Chevy
Satisfied Customers: 2158
Experience:  GM
Type Your Chevy Question Here...
GMTechBernard is online now
A new question is answered every 9 seconds

Hi, I have 2003 cadillac deville. 1) The check coolant ...

Resolved Question:

Hi, I have 2003 cadillac deville. 1) The check coolant level always comes on. The coolant level is fine. What could it be? how do I reset? 2) check engine light on I believe it says secondary air injection. I will put on the code tester for number.   Can you give me some insight. This is my father in laws car and its driving him crazy in turn driving me crazy. HA HA
Submitted: 7 years ago.
Category: Chevy
Expert:  GMTechBernard replied 7 years ago.

If the coolant level is correct, then the level sensor is likely suspect. The level sensor is part of the coolant jug assembly, and would require replacement of the jug, it plugs in at the bottom:



As for the secondary air injection code, first you want to check the fuses. If the air pump sucks up some water, it will blow the fuse.

Then you want to check your vacuum lines. There is a shutoff valve going to the front exhaust and one to the rear exhaust, and they are both controlled by vacuum. Sometimes the vacuum lines can fall off or crack and not allow the valves to open.

If thats all OK, check to see if you hear the pump come on. When you first start the car, especially after not being started for awhile, you should hear the pump run for a minute or two. Sounds like a small motor, it kinda whines/whistles like a hair dryer or little supercharger. If you hear it come on for a minute or two and shut off, then the air pump is obviously coming on and it may be one of the shutoff valves that failed. Its common for the diaghram inside the valve to rupture which prevents the vacuum from letting it open.

This is where the front valve is located, the rear valve looks the same and is over the center of the back valvecover:


Customer: replied 7 years ago.
Reply to GMTechBernard's Post: Thanks

Coolant issue:
1) checked all fuses. All good.
2) I checked plug harness no power even on one side. Shouldn't there be? at least coming in and if switch bad would not be coming out. where might be the issue?

Codes I ran check:

Po 340 camshaft pos sensor bank 1 malfunction

po 410 second air injection system malfuntion

po 420 catalyst efficiency below threshold bank 1

Then 410 and 420 repeat on scanner w on diff showing a pd in window.

I checked what you said. I had one question directly in back of engine is a small black hose and one larger rubber hose connected to looks like a vacumm circle. These two are very loose. The lower black hose has a hose clamp but not upper(very loose) small elbow on vacumm very loose.

Thank You for your time and I will compensate.

Expert:  GMTechBernard replied 7 years ago.

As for the coolant level, it sends out a very low voltage from the cluster to ground. The easiest way to diagnose is to put a jumper wire between the two terminals and if the message goes out, the level sender is bad.

The P0420 means you have a bad catalytic converter, and is covered under the Federal 8 year/ 80,000 mile warranty. If you have 80K or less, you can get it repalced at the cadillac dealer at no charge.

Customer: replied 7 years ago.
Can the coolant message come on if it is too full. I spilt some out while getting harness off and put it all back and the message seems to be gone.

I just changed caty. conv last year because it was just over 80k but now at 100k I did put an after market pump in.

How about the lines in back of engine. They are related to vacumm should they be tight?

One last question at about 50-60 he gets a shimmy on brakes changed pad rotor not too long ago. looked at this morning seem fine. could he have warped rotors. (they were advance autos)
Expert:  GMTechBernard replied 7 years ago.

The message won't come on if too full, only low (or bad).

Aftermarket cat converters rarely have enough Oxygen Storage Capacity to satisfy the stringent diagnostic parameters of the On-Board Computer. On many of the newer cars, only a GM converter will work. You could do a search on-line for "O2 Simulators". They "trick" the computer into thinking the converter is working and prevents the P0420 from setting.

The lines on the back of the motor need to be tight. Air of Vacuum leaks can prevent the system from working properly.

As for the brake shimmy, some aftermarket rotors are better than others. If you spend $15 per rotor, chances are, they will warp rather soon. When it comes to brake components, you really do get what you pay for. Instead of replacing them, you can have them resurfaced.

GMTechBernard, Shop Foreman - GM World Class Tech
Category: Chevy
Satisfied Customers: 2158
Experience: GM
GMTechBernard and 2 other Chevy Specialists are ready to help you
Customer: replied 7 years ago.
Reply to GMTechBernard's Post: Thank you so much for your help today.

After I tightened the vacumm stuff no more lights came on nor did the o2 sensor. Although I only drove it for about 1 hr.

How do you install an 02 simulator if It comes on again. I will need a sticker at end of month and the engine light cant be on.

Im hitting accept after this message.

Thanks Again.

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... seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like
...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 was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
< Previous | Next >
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland

Meet The Experts:

  • GM Tech (Cam)

    GM Tech (Cam)

    Chevy Technician

    Satisfied Customers:

    GM Grand Master Technician 2007. 14 years experience.
< Last | Next >
  • GM Tech (Cam)'s Avatar

    GM Tech (Cam)

    Chevy Technician

    Satisfied Customers:

    GM Grand Master Technician 2007. 14 years experience.
  • Tim's Auto Repair's Avatar

    Tim's Auto Repair


    Satisfied Customers:

    Have owned a repair shop for 25 yrs.
  • Gary's Avatar


    Chevy Technician

    Satisfied Customers:

    15 years GM master tech
  • Dave Nova's Avatar

    Dave Nova

    Chevrolet Technician

    Satisfied Customers:

    ASE Master Certification. GM World Class Certification
  • John's Avatar


    Master A.S.E Automotive technician

    Satisfied Customers:

    A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
  • Don 'Mo Lurch''s Avatar

    Don 'Mo Lurch'

    Auto Mech / Electronics

    Satisfied Customers:

    Chevrolet Cert., Heavy Line Mech, Race Shop Owner, Mobile Electronics.
  • Ron Z.'s Avatar

    Ron Z.

    - Chevy Tech -

    Satisfied Customers:

    18+yrs experience. State Inspector and Chevy Diagnostics