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Ask Chris(aka-Moose) Your Own Question
Chris(aka-Moose), Nissan Technician
Category: Nissan
Satisfied Customers: 615
Experience:  16 years of experience
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I recently purchased a used 2002 nissan sentra se-r and

Customer Question

Hello, I recently purchased a used 2002 nissan sentra se-r and experience a P0420 OBC Code reading. I replace the temp sensor, oil change and radiator coolant and still experiencing the temp gause fluctuating intermitently between the high temp and low temp setting.
JA: Sometimes things that you think will be really complicated end up being easy to fix with a Nissan. The Nissan Mechanic I'm going to connect you with knows all the tricks and shortcuts. Are you hoping to fix this yourself?
Customer: Yes.
JA: Great! What have you tried so far?
Customer: Temperature sensor changed. Coolant and oil changed.
JA: Is there anything else the Nissan Mechanic should be aware of about your Nissan?
Customer: no
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Nissan Mechanic about your situation and then connect you two.
Submitted: 1 year ago.
Category: Nissan
Expert:  Jay replied 1 year ago.

Hello my name is ***** ***** thank you for your question.

The P0420 is a Catt Converter code. Is this a 1.8 engine? How did you bleed the coolant system? These systems are tricky to bleed. This why I am asking?

Let me know

Customer: replied 1 year ago.
it is a 2.5L Manual Transmission 2002 Nissan Sentra
Customer: replied 1 year ago.
I was pressing on the hoses to release the air trapped in the cooling system.
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Help via Email or Text Message. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Jay replied 1 year ago.

You will need to bleed the coolant system for around 1/2 hour to a hour. Let me explain how you do it so you can try it. Give me time to type it all out

Expert:  Jay replied 1 year ago.

To bleed the coolant system, remove the radiator cap. Install the coolant bucket ( See Links for images ). Fill the bucket about 1/2 way. Then raise the front of the car as high as if it were on ramps. This way if there is air in the coolant system, the circulation brings it to the highest point. Then turn on the car, and put the heat on speed number 4, recirc mode on, and face mode. You may need to rev the engine a few times to move the coolant around to get the air out. I also turn the engine off a couple times and wait 2 or 3 mins to let the air pocket move and bubble out. In the mean time you want to check your vents to see if your getting heat. After you have good heat, and little to no bubbles in the coolant bucket. Then the coolant system is properly bleed. You should have good heat when bleed properly. So when you put your hand over the vent and hold it there for 30 seconds, you get a slight burning sensation. That is perfect heat

If you can't get a coolant bucket, you can use a funnel the same way, you just may need to pinch off the over flow bottle hose.

Expert:  Jay replied 1 year ago.

Give that a try and let me know how you make out..