Contour Enthusiasts Group Archives Forums General Troubleshooting PO420

Its been a couple of weeks since I last reset computer from previous PO420. Light came back on again. I'm assuming its the going to be the same code - did some researching in the archives concerning the PO420 code and realize it's the O2 sensor or cat. Bought the O2 sensor for the front manifold and wondering if the rear manifold sensor is the same? I bought the sensor thinking I had to replace the sensor on the f. manifold, but after reading the archives, saw that many people replaced the one on the rear. Called Ford and store where I purchased sensor from and neither have been much help. Ford lists only two sensors and Advance Auto lists three, and none of which have the listing of O2 sensor for r. manifold.

P0420 Catalyst System Efficiency below Limit - Bank No 1.

Bank 1 is closest to the firewall. I believe this code will be caused by a bad reading from the downstream sensor, which is easiest to reach from under the car. Could also be a bad pre-cat. You could swap the downstream sensors between the front and rear manifolds to see if the problem moves to the other bank.

http://www.contour.org/FAQ/FAQ.cgi?s=probs&display=checkengine

When I got the same code, Ford replaced all three cats on their nickel. Warranty on the cats is 80K miles.

the reason the auto store list 2 is becasue up to a certain year, the duratechs used a certain sensor. In 1999 they changed the sensor. So some SVT's had one sensor and some had another. But the sensor befor the Pre-Cat's always remains the same. I have the Bosch Numbers for you to reference.

production date: up to 1/2/99
before pre-cat part # 13115 after pre cat #13133

production date: 1/2/99 and on
before Pre cat part # 13115 after precat # 13201

As you can see that the only one that changes on the spacific date is the ones after the cats.

Bank 1 is the Pre-cat next to the fire wall
Bank 2 is the cat in front.

I hope you can use the info I provided. Remember these are Bosch part numbers...I don;t have a cross referance for OE.

Roz

I am so confused, so please have patience with me. I take it that the O2 sensor closest to the firewall is the Bosch 13201? - my car was made after the later date. When I look under the car, I see two other O2 sensors near the "Y" split - is the one on the pipe going to the front manifold Bank 2 and therefore the Bosch 13115? If this is correct, if I wanted to replace all four of my sensors, I would have to buy two 13115's and two 13201's? Thanks for educating me on this matter.

I've spent some time drawing pictures to understand location and language of how to correctly identify the O2 sensors, and I think I understand now. Both of the "downstream" sensors, near the "Y" split (after the pre-cats) - would be the Bosch 13201 sensors? Both of the sensors near the top of the engine or "upstream" sensors (before the pre-cats) - would then be Bosch 13115? In other words, on Bank 1 there would be a 13115 near the top of the engine and a 13201 underneath the engine? And the same for Bank 2?

Hey bro...sorry if i confused you here is the simple....

Since your car was made on the later date you would use:

before Pre cat part # 13115 after precat # 13201

On a V6 duratech, the car has 2 Pre Cat;'s on the exahust manifold, before it goes to the Main cat under the car.

There are 4 o2 sensors on a v6. 1 before each Pre-cat and one after each pre cat for a total of 4.

if its the one after the pre cat you will use part number

13201. The other number is for the sensor before the pre cat.

Now...Bank 1 means its the precat next to your fire wall.
Bank 2 means the pre-cat next to your radiator.


so if the code say "pre-cat,bank one" the you would change the bottom O2 sensor (or cat...ford codes are not very accurate)on the precat next to the fire wall.

I hope that clarafied things...if you want me to explain over the phone, PM me and i will give my number. Writing is so hard to explain things.

ROZ

Thanks a bunch for your help and explanation on the location of the O2 sensors - all is clear to me now. This site/forum has been an invaluable resource in this, my time of need. Maybe now I can return the favor with some additional information regarding the O2 sensors.

Bosch #13201 corresponds with Motorcraft #DY-850 and lists for $100.54.

Bosch #13115 corresponds with Ford #X52Z-9G4444-AA.

Hey thanks for the info! Hey I might be able to get you a discount on the O2 sensors ( I work in wholesale..Im a Buyer) Let me look into it and I'll let you know...PM me later.

Roz

I did the exact same thing one month ago [code 420]

all is OK

Good luck