P0420 SES Code ---- Help!!
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Donating Maxima.org Member
Joined: Dec 2000
Posts: 200
P0420 SES Code ---- Help!!
2K1 Max with 58k. SES light came on. Dealer reprogrammed/updated the ECU. Now at 59k, SES light on again for several days (200 miles of driving). This morning, starting up the car to go to dealer to get SES light checked out again, SES light does not come on. I go to dealer anyway. Dealer pulls a P0420 code and tells me I need a new cat converter for $1,000+ and that this repair not covered under extended emissions warranty. I leave.
Yes, I've done 'search', but still looking for advice:
* ECU already updated, but light came back on, so the TSB mentioned in other posts does not appear to be the answer.
* SES light now out on its own (see above). Think it will come back on? What would cause it to go out when it had been on for several days?
* If I do need a new cat converter, isn't this covered under the long-term emmisions warranty (80,000 miles)?
* Some posts mention that the problem is really O2 sensors. Don't want to spend $$ on new O2 sensors if this is not really the problem. How do I tell?
Thanks for any ideas/advice.
Yes, I've done 'search', but still looking for advice:
* ECU already updated, but light came back on, so the TSB mentioned in other posts does not appear to be the answer.
* SES light now out on its own (see above). Think it will come back on? What would cause it to go out when it had been on for several days?
* If I do need a new cat converter, isn't this covered under the long-term emmisions warranty (80,000 miles)?
* Some posts mention that the problem is really O2 sensors. Don't want to spend $$ on new O2 sensors if this is not really the problem. How do I tell?
Thanks for any ideas/advice.
Supporting Maxima.org Member
Joined: May 2002
Posts: 1,815
From: Atlanta
Re: P0420 SES Code ---- Help!!
P0420 = Catalyst System Efficiency Below Threshold (Bank 1)
I'm just guessing here but I believe (Bank 1) = cyls 1,3,5. And that this would be a PreCat issue. If someone else has more info please post.
Based on your list of mods I don't see how you could have voided your 10yr. 100,000mi. Emmisions warranty which this should be covered under. And doesn't this warranty cover o2 sensors through that term also?
If the light is out it is because after a certain number of drive cycles, I am not sure of how many, if the ECU doesn't see the same problem the light goes off but the code is still stored. It will come back on again if an o2 sensor trips the right voltage. This could be a bad cat, a bad o2 sensor or even a loose connection at either end of an o2 sensors wire lead.
I would either take it to another dealer or ask to talk to the service manager at the dealer you took it to.
Hope this helps.
I'm just guessing here but I believe (Bank 1) = cyls 1,3,5. And that this would be a PreCat issue. If someone else has more info please post.
Based on your list of mods I don't see how you could have voided your 10yr. 100,000mi. Emmisions warranty which this should be covered under. And doesn't this warranty cover o2 sensors through that term also?
If the light is out it is because after a certain number of drive cycles, I am not sure of how many, if the ECU doesn't see the same problem the light goes off but the code is still stored. It will come back on again if an o2 sensor trips the right voltage. This could be a bad cat, a bad o2 sensor or even a loose connection at either end of an o2 sensors wire lead.
I would either take it to another dealer or ask to talk to the service manager at the dealer you took it to.
Hope this helps.
Re: P0420 SES Code ---- Help!!
Originally posted by jnovember
2K1 Max with 58k. SES light came on. Dealer reprogrammed/updated the ECU. Now at 59k, SES light on again for several days (200 miles of driving). This morning, starting up the car to go to dealer to get SES light checked out again, SES light does not come on. I go to dealer anyway. Dealer pulls a P0420 code and tells me I need a new cat converter for $1,000+ and that this repair not covered under extended emissions warranty. I leave.
Yes, I've done 'search', but still looking for advice:
* ECU already updated, but light came back on, so the TSB mentioned in other posts does not appear to be the answer.
* SES light now out on its own (see above). Think it will come back on? What would cause it to go out when it had been on for several days?
* If I do need a new cat converter, isn't this covered under the long-term emmisions warranty (80,000 miles)?
* Some posts mention that the problem is really O2 sensors. Don't want to spend $$ on new O2 sensors if this is not really the problem. How do I tell?
Thanks for any ideas/advice.
2K1 Max with 58k. SES light came on. Dealer reprogrammed/updated the ECU. Now at 59k, SES light on again for several days (200 miles of driving). This morning, starting up the car to go to dealer to get SES light checked out again, SES light does not come on. I go to dealer anyway. Dealer pulls a P0420 code and tells me I need a new cat converter for $1,000+ and that this repair not covered under extended emissions warranty. I leave.
Yes, I've done 'search', but still looking for advice:
* ECU already updated, but light came back on, so the TSB mentioned in other posts does not appear to be the answer.
* SES light now out on its own (see above). Think it will come back on? What would cause it to go out when it had been on for several days?
* If I do need a new cat converter, isn't this covered under the long-term emmisions warranty (80,000 miles)?
* Some posts mention that the problem is really O2 sensors. Don't want to spend $$ on new O2 sensors if this is not really the problem. How do I tell?
Thanks for any ideas/advice.
Some dealers may say they reprogramed your ECU, but as I found with MY experience, they could not on their first attempt. Your dealer may have attempted to do the reprogramming, but failed and just told you they did. Instead they just cleared the codes and that's why it came back. Your situation is exactly why the TSB for the oversensitive 02 measurements exists. IF your cat was bad, your MIL would NOT turn on and off.
I would go to ANOTHER dealer and tell them to check if your ECU has the latest PART NUMBER using a Consult-II, however being that your over 36K miles, I doubt it will be under warranty. Was it warrantied at 58K? If it's found to NOT be the latest part number, I'd have a little "talk" with your current dealer. If they refuse to perform the latest TSB, I'd pay for the update which is quoted for 30-mins.. It SHOULD NOT TAKE MORE THAN 15mins., but they always add in time for BS.
HERE is why I'm claiming Dealership BS.....
According to TSB NTB00-070a on March 15, 2001 for "2000-2001 Maxima MIL "ON" with DTC P0420 Stored 3-Way Catalyst Function"
[TSB]
SERVICE INFORMATION
If an applied 2000-2001 Maxima has a MIL "ON" with DTC P0420(Three Way Catalyst Fuction) stored in the ECM, it may be the result of an internal ECM Program Misdiagnosis. The catalyst should not be replaced.[edit: it's in bold in the TSB even!] This bulletin provides updated ECM data to reprogram the vehicle's ECM to correct the condition.
[/TSB]
Affected Vehicles:
----------------------
Vehicle: 2001, M/T, w/V-tires
Current ECM P/N: 23710-4Y910, -4Y911, -4Y912
New ECM Data P/N: 23710-4Y913
[TSB]
SERVICE INFORMATION
If an applied 2000-2001 Maxima has a MIL "ON" with DTC P0420(Three Way Catalyst Fuction) stored in the ECM, it may be the result of an internal ECM Program Misdiagnosis. The catalyst should not be replaced.[edit: it's in bold in the TSB even!] This bulletin provides updated ECM data to reprogram the vehicle's ECM to correct the condition.
[/TSB]
Affected Vehicles:
----------------------
Vehicle: 2001, M/T, w/V-tires
Current ECM P/N: 23710-4Y910, -4Y911, -4Y912
New ECM Data P/N: 23710-4Y913
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