1996 Sable - EGR insufficient flow and bank 1 O2 sensor

[DonNanneman]

My CEL is on OBDII reader shows O2 sensor failure bank one and insufficient flow EGR

I had some preliminary checks done - the EGR valve is good and tubing not carboned up.

These parts are on back (firewall) side of engine - Can anyone tell me how much work it will bee to access these to replace?

Thanks!

[MT-2500]

Originally Posted by DonNanneman

My CEL is on OBDII reader shows O2 sensor failure bank one and insufficient flow EGR

I had some preliminary checks done - the EGR valve is good and tubing not carboned up.

These parts are on back (firewall) side of engine - Can anyone tell me how much work it will bee to access these to replace?

Thanks!

Proceed with caution .
Codes do not say replace parts.
What was the code no.
Egr problems can be in the DPFE sensor or feed pipe or Intake ports stopped up.
What engine and what codes?

[DonNanneman]

Here are the codes
P0135 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
P0401 Exhaust Gas Recirculation Flow Insufficient Detected

I do not know if there are more specific mfg/proprietary codes to narrow these down further?

Don

[DonNanneman]

I replaced the O2 sensor - accessed it from top of engine after removing cabin air intake cowl/duct and coil pack. Bit of a pain with straight wrench - needed offset open end wrench.
Found out that who-ever installed pevious sensor wasn't very careful the wires were twisted with damaged insulation and external center 'barrel' of sensor was bent.

[shakewell]

i had same codes on my '01 and it was the dpfe sensor. if the codes come back, replace the sensor - it's a snap.

[DonNanneman]

I chnged the sensor - code came back in a week, re-set code and it came back on again in 9 days.

Plan to look at it again this sATURDAY - aNY SUGGESTIONS OF WHERE TO LOOK?

dON

[MT-2500]

Originally Posted by DonNanneman

I chnged the sensor - code came back in a week, re-set code and it came back on again in 9 days.

Plan to look at it again this sATURDAY - aNY SUGGESTIONS OF WHERE TO LOOK?

dON

What code and what engine?

[Slade901]

More than likely you have a failing catalytic converter. You can just purchase a catalytic converter http://autopartswarehouse.com/ and have someone at a welding shop remove the defective catalytic converter and put the new catalytic converter ($50) Free shipping over $50.

[DonNanneman]

Originally Posted by MT-2500

What code and what engine?

Code P0401

engine druatec 3.0 DOHC

[DonNanneman]

Originally Posted by Slade901

More than likely you have a failing catalytic converter. You can just purchase a catalytic converter http://autopartswarehouse.com/ and have someone at a welding shop remove the defective catalytic converter and put the new catalytic converter ($50) Free shipping over $50.

What is the connectio of the cat to the EGR flow sensor?

Don

[Slade901]

Most newer vehicles have two O2 sensors. One upstream (before the cat) and one downstream (after the cat). If the cat honey combs is broken apart inside, it could allow the exhaust to get past the cat faster and O2 sensor upstream will not be able to monitor properly or report insufficient gas/exhaust/02 mixture. If you got two cats then you got four O2 sensors as well. On mine over time after seeing 02 code and replacing the 02, I listened underneath the vehicle and I could hear the metal inside on one of the cat rattling and I have it replaced and it fixed the 02 code.

[Slade901]

Originally Posted by DonNanneman

What is the connectio of the cat to the EGR flow sensor?

Don

As you can see, the EGR gas is the same exhaust gas that is suppose to go to the catalylic converter. Since the EGR pipe is connected to the same exhaust pipe upstream of the cat, some of the exhaust gas is directed to the EGR pipe for emmission purposes (help clean the environment) and goes back to your intake manifold and get burned again in the combustion chamber (no wonder why the intake manifold gunked up pretty quickly) and the rest of the exhaust goes to the cat.

[MT-2500]

Originally Posted by DonNanneman

Code P0401

engine druatec 3.0 DOHC

If egr valve ports are open and egr valve is working and vacuum good and solenoid is working.
The next most common problem is the DPFE sensor or hoses to to.
If the old silver one remove it and look for a lot of corrosion where the exhaust pressure line go into it.
If stopped up or dirty in there you might as well replace it.
And check for a recall or updated black plastic one.
MT

[DonNanneman]

Originally Posted by Slade901

Most newer vehicles have two O2 sensors. One upstream (before the cat) and one downstream (after the cat). If the cat honey combs is broken apart inside, it could allow the exhaust to get past the cat faster and O2 sensor upstream will not be able to monitor properly or report insufficient gas/exhaust/02 mixture. If you got two cats then you got four O2 sensors as well. On mine over time after seeing 02 code and replacing the 02, I listened underneath the vehicle and I could hear the metal inside on one of the cat rattling and I have it replaced and it fixed the 02 code.

Sorry for my confusing heading

the O2 sensor upstream (heater circuuit) code is gone
Just the EGR insufficient flow 0401 code now.
I do have trouble seeing how cat could effect either
It won't effect the composition of gas they are exposed to
it could effect backpressure which should increase, not decrease EGR flow - right?

[Slade901]

Plugged up cat = increase backpressure
Broken honey comb inside the cat = less than normal backpressure
working cat = normal within range backpressure