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Discussion Starter #1
I have an 04 ssr with 136000 miles. The check engine light comes on about 2 days after I clear it. I replaced the bank 1 sensor 1 with a demos O2 sensor. Because my diagnostic tool said it was the problem. Now I get 2 P0420 codes. Both saying bank 1 and no sensor number. I ran car clean through it and put seafoam in the tank when I filled up after running the cat clean through. 3 days later the 2 P0420 codes showed up again. Haven't noticed any changes in the way she runs. Any help from here please.?
 

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What code did you get that said "bank1, sensor 1 bad"
2 P0420 - codes? This is the same code, it is being displayed twice. Not sure what kind of code reader you purchased but, if is the reason for replacing sensor 1. The code reader cost you more money than its actual purchase.
Not sure what is a demos O2 sensor?

P0420 is a catalyst deficiency For bank 1. The computer monitors the upstream and downstream O2 sensors for proper voltage swings AFTER it is sure all engine operating parameters are good. the downstream 02 is functioning but incorrectly it can cause computer to assume catalytic converter is degraded.

In summary it is most likely caused by either a defective downstream O2 (including heater and other wiring associated with it) or a defective converter.
More complete somewhat complicated tests required to determine for sure. Cheapest GUESS is Downstream sensor. Although I would not rule out a converter with the high mileage and not history. If car had been driven for awhile with a problem (bad plug, wire, etc) this can lead to a converter problem. Might be better off paying a diagnostic fee than guessing.
Sorry.
 

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I have an 04 ssr with 136000 miles. The check engine light comes on about 2 days after I clear it. I replaced the bank 1 sensor 1 with a demos O2 sensor. Because my diagnostic tool said it was the problem. Now I get 2 P0420 codes. Both saying bank 1 and no sensor number. I ran car clean through it and put seafoam in the tank when I filled up after running the cat clean through. 3 days later the 2 P0420 codes showed up again. Haven't noticed any changes in the way she runs. Any help from here please.?
A way of looking at it:
The Upstream O2 (sensor 1) reads input (into the converter), while the downstream (rear -sensor 2) reads the output.
The front sensor readings typically fluctuate while the rear typically run pretty steady.

If there isn’t a sufficient difference between what’s going in versus what’s coming out, the computer thinks the converter isn’t doing it’s job.
The issue can be either sensor or even the converter itself. However, the front sensor technically only reads input and the P0420 code is for a converter issue (converter being downstream of the front sensor).

Without a scope or a real-time data scanner to diagnosis the sensors, it’s a guess. Personally, I’ve seen the P0420 tend to be the rear sensor or the converter.
Considering the labor/cost of a new converter; I wouldn’t hesitate trying a new rear sensor first.
 

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Discussion Starter #4 (Edited)
It was a p0420 code that said bank 1 sensor 1. I have a Innova 3100 diagnostic reader. It always takes several trips and days for it to come back on again after clearing it. That's the puzzling part. I feel the computer wouldn't take that long to show a problem part like a bad O2 sensor. I'm a electrical technician, so I have electrical test equipment to help solve this. I hope...what I really need is a schematic for 04 ssr wireing. Being I live in Illinois and it's winter here. Like to know if it's an intermittent connection and that's why it takes so long to show the code again. My reading on the bank 1 sensors is that the computer uses it to determine the fuel mix with air. That's my concern about driving it with the engine light on with code p0420. That it might run a little richer and take out the catalytic. Thank you for all your help.
 

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SStack: Had the same problem on mine about 7 years ago. It ended up being rear sensor. Only difference is code came and went...I suspected and changed rear sensor and never got a code again and the A/R was dead on.
 

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I forgot to mention
Welcome to the site. You will find a lot of people here that will try to help.

from factory service manual

Regarding your Code definition
P0420 Catalyst System Low Efficiency (Bank 1) - Automatic Transmission

How the computer uses the O2 sensors
Circuit Description

The three-way catalytic converter (TWC) reduces emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx). The catalyst within the converter promotes a chemical reaction, which oxidizes the HC and CO that are present in the exhaust gas. This process converts these chemicals into water vapor and carbon dioxide (CO2), and will reduce the NOx, by converting them into nitrogen. The catalytic converter also stores oxygen. The powertrain control module (PCM) monitors this process using heated oxygen sensor (HO2S) bank 1 sensor 2 and HO2S bank 2 sensor 2, located in the exhaust stream after the TWC. These sensors are referred to as the catalyst monitor sensors. The catalyst monitor sensors produce an output signal the PCM uses to indicate the oxygen storage capacity of the catalyst. This determines the catalysts ability to effectively convert the exhaust emissions.

If the catalyst is functioning correctly, the HO2S bank 1 sensor 2 and HO2S bank 2 sensor 2 signals will be far less active than the signals that are produced by HO2S bank 1 sensor 1 and HO2S bank 2 sensor 1. This indicates that the TWC oxygen storage capacity is at an acceptable threshold. When the response time of the catalyst monitor sensors are close to that of the fuel control sensors, the ability of the catalyst to store oxygen may be below an acceptable threshold.

The PCM performs this diagnostic test at idle. When the conditions for running this DTC are met, the following occurs:

The air-to-fuel ratio transitions from lean to rich.
The air-to-fuel ratio transitions from rich to lean, opposite the first air-to-fuel ratio transition.
The PCM captures the response time of the front and the rear HO2S when the air-to-fuel ratio transitions occur. The HO2S response time changes from less than 350 mV to more than 600 mV, and from more than 600 mV to less than 350 mV.
The PCM measures the time necessary for the rear HO2S voltage to cross a reference lean-to-rich threshold, and the time necessary for the front HO2S voltage to cross the same lean-to-rich threshold. The difference between the front HO2S time and the rear HO2S time indicates the oxygen storage capacity of the catalyst. If the PCM detects that this time difference is less than a predetermined value, DTC P0420 for bank 1 or DTC P0430 for bank 2 sets.

What conditions have to be met and tested for a problem BEFORE the computer tests for this problem -- why it takes so long to reoccur

Conditions for Running the DTC

DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0125, P0128, P0131, P0132, P0133, P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0151, P0152, P0153, P0154, P0155, P0156, P0157, P0158, P0160, P0161, P0171, P0172, P0174, P0175, P0200, P0220, P0300, P0325, P0327, P0332, P0335, P0336, P0341, P0342, P0343, P0351–P0358, P0442, P0443, P0446, P0449, P0452, P0453, P0455, P0496, P0502, P0503, P0506, P0507, P1125, P1133, P1134, P1153, P1154, P1516, P2101, P2108, P2120, P2121, P2125, P2135 are not set.
The engine has been running for more than 10 minutes.
The intake air temperature (IAT) is between -7 to +85°C (+20 and +185°F).
The barometric pressure (BARO) is more than 75 kPa.
The engine coolant temperature (ECT) is more than 70–120°C (158–248°F).
Since the end of the last idle period, the engine speed has been more than 900 RPM for 46 seconds.
The engine must be at a stable idle speed, within 200 RPM of desired idle.
The battery voltage is more than 10.7 volts.
The Closed Loop fuel control is enabled.

I hope this helps
You should contact Dinerman and purchase an ultimate drive -- see link
http://www.ssrfanatic.com/forum/f22/ultimate-drive-149170/

Again welcome from central Ohio
 

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The help will keep coming but meantime--Welcome from Forney Texas!!! Go to "Tools" in the red banner, click on "User CP" go to "Your Profile" then click "Edit Your Details". Then, whenever you "post" it will show in the left column under your name, like the rest of us, and we will know where you are and what you drive. Then if you have a problem, someone close by might be able to help out.

Nick & Kathy
 

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I just had the same problem.
I replaced all 4 sensors with Bosch Premium Direct Fit OE Sensors because I've had terrible luck with the new stock AC Delco and GM parts lately..Real difference in quality from old stock parts versus new stock.
2005 SSR runs much smoother and is much quicker.
Here is the link to the Post Parts Finder:https:
//www.boschautoparts.com/en/
Good luck.
 

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Discussion Starter #11
Had it tested at a dealer and they said it was the catalytic coverter. Thank you everyone so much... my new problem is my speedometer. It started when it got to -15 degrees here. It was reading 70 when I was stopped and moved up when moving. I kept restarting the engine and it got back to normal. Then today after a nother night of minus temps. It is all the way past 140 and not getting better. My gas hasn't worked for awhile. Think it's the servo. Any one know where I can get these?
 

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my new problem is my speedometer. It started when it got to -15 degrees here. It was reading 70 when I was stopped and moved up when moving. I kept restarting the engine and it got back to normal. Then today after a nother night of minus temps. It is all the way past 140 and not getting better. My gas hasn't worked for awhile. Think it's the servo. Any one know where I can get these?
I know what you mean on the - temps. I'm just up the road a bit from you and my truck had no power steering (or any steering) nor Brakes when I first fired it up this morning. Let her warm up for 15 minutes and she began working better.
 
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