O2 and catalytic converter CEL
03-17-2016, 05:51 AM
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O2 and catalytic converter CEL
Good evening everyone,
I've made several searches but I haven't run across one that addresses this specifically or has a resolution. Here goes:
Our new to us 2005 Cayenne V6 3.2L, 6-speed manual w/ 91,700 miles (we bought it with 82,000 miles) runs great and has given no problems for the first 6-8 months of ownership. It then gave a random CEL which I read with the Durametric to be:
P2237
Lambda control adaptation at idle, Bank 2 - Upper limit value exceeded, test conditions are not-completed, fault is not currently active and is not causing a DTC light
P2237
Lambda control adaptation at idle, Bank 2 - No signal/communication, test conditions are not-completed, fault is currently active and causing a DTC light
P2235
Lambda control adaptation at idle, Bank 1 - Upper limit value exceeded, test conditions are not-completed, fault is not currently active and is not causing a DTC light
P2235
Lambda control adaptation at idle, Bank 1 - No signal/communication, test conditions are not-completed, fault is currently active and causing a DTC light
I reset it once, switched gasoline stations (using premium 91-92 at all times) and it comes back about 4 weeks later. I change the gas cap, reset it and it comes back 3 weeks later. Searched forums and was basically looking at replacing my O2 sensors. Replaced the pre-cat sensors, cleaned the MAF and reset. CEL returned 2 weeks later. Replaced post-cat sensors and found a couple of the plastic vacuum lines had cracked next to the intake manifold. Repaired the vacuum lines, reset the CEL and it went away for almost 3 weeks. Unfortunately the CEL came back with this:
P0421
Catalyst System Efficiency Below Threshold Bank 1 - Upper limit value exceeded, test conditions are not-completed, fault is currently active and causing a DTC light
P0431
Catalyst System Efficiency Below Threshold Bank 2 - Upper limit value exceeded, test conditions are not-completed, fault is not currently active and causing a DTC light
So now I'm thinking catalytic converters but I do a bit more searching and one thread mentions that for catalytic converter to fail so early something may be causing it to fail. So now I've replaced the MAF and plugs (mainly because I don't know when the plugs were replaced last), reset CEL and it came back 3-4 days later with all of the codes:
P0421
Catalyst System Efficiency Below Threshold Bank 1 - Upper limit value exceeded, test conditions are not-completed, fault is currently active and causing a DTC light
P0431
Catalyst System Efficiency Below Threshold Bank 2 - Upper limit value exceeded, test conditions are not-completed, fault is not currently active and causing a DTC light
P2237
Lambda control adaptation at idle, Bank 2 - Upper limit value exceeded, test conditions are not-completed, fault is not currently active and is not causing a DTC light
P2237
Lambda control adaptation at idle, Bank 2 - No signal/communication, test conditions are not-completed, fault is currently active and causing a DTC light
P2235
Lambda control adaptation at idle, Bank 1 - Upper limit value exceeded, test conditions are not-completed, fault is not currently active and is not causing a DTC light
P2235
Lambda control adaptation at idle, Bank 1 - No signal/communication, test conditions are not-completed, fault is currently active and causing a DTC light
So I'm back at the catalytic converters again which I'm fine with doing, but here are my questions:
1. Do catalytic converters fail this soon on a low mileage vehicle?
2. Why would the P2237/2235 codes come back?
3. Any ideas on what I may be missing? More vacuum leaks, ECM issues, etc?
Lastly as a side note, when changing plugs, I inspected the coils and they all looked fine (i.e. no obvious cracks, wiring in good shape, etc) but I did notice small oil build up on the top of the plugs (none in the cylinders - plugs looked normal). Is that indication of a leaky valve cover gasket and would that be related to any of my issues?
Sorry for the long post - just wanted to be thorough. Any help or insight would be greatly appreciated. Thanks everyone...
I've made several searches but I haven't run across one that addresses this specifically or has a resolution. Here goes:
Our new to us 2005 Cayenne V6 3.2L, 6-speed manual w/ 91,700 miles (we bought it with 82,000 miles) runs great and has given no problems for the first 6-8 months of ownership. It then gave a random CEL which I read with the Durametric to be:
P2237
Lambda control adaptation at idle, Bank 2 - Upper limit value exceeded, test conditions are not-completed, fault is not currently active and is not causing a DTC light
P2237
Lambda control adaptation at idle, Bank 2 - No signal/communication, test conditions are not-completed, fault is currently active and causing a DTC light
P2235
Lambda control adaptation at idle, Bank 1 - Upper limit value exceeded, test conditions are not-completed, fault is not currently active and is not causing a DTC light
P2235
Lambda control adaptation at idle, Bank 1 - No signal/communication, test conditions are not-completed, fault is currently active and causing a DTC light
I reset it once, switched gasoline stations (using premium 91-92 at all times) and it comes back about 4 weeks later. I change the gas cap, reset it and it comes back 3 weeks later. Searched forums and was basically looking at replacing my O2 sensors. Replaced the pre-cat sensors, cleaned the MAF and reset. CEL returned 2 weeks later. Replaced post-cat sensors and found a couple of the plastic vacuum lines had cracked next to the intake manifold. Repaired the vacuum lines, reset the CEL and it went away for almost 3 weeks. Unfortunately the CEL came back with this:
P0421
Catalyst System Efficiency Below Threshold Bank 1 - Upper limit value exceeded, test conditions are not-completed, fault is currently active and causing a DTC light
P0431
Catalyst System Efficiency Below Threshold Bank 2 - Upper limit value exceeded, test conditions are not-completed, fault is not currently active and causing a DTC light
So now I'm thinking catalytic converters but I do a bit more searching and one thread mentions that for catalytic converter to fail so early something may be causing it to fail. So now I've replaced the MAF and plugs (mainly because I don't know when the plugs were replaced last), reset CEL and it came back 3-4 days later with all of the codes:
P0421
Catalyst System Efficiency Below Threshold Bank 1 - Upper limit value exceeded, test conditions are not-completed, fault is currently active and causing a DTC light
P0431
Catalyst System Efficiency Below Threshold Bank 2 - Upper limit value exceeded, test conditions are not-completed, fault is not currently active and causing a DTC light
P2237
Lambda control adaptation at idle, Bank 2 - Upper limit value exceeded, test conditions are not-completed, fault is not currently active and is not causing a DTC light
P2237
Lambda control adaptation at idle, Bank 2 - No signal/communication, test conditions are not-completed, fault is currently active and causing a DTC light
P2235
Lambda control adaptation at idle, Bank 1 - Upper limit value exceeded, test conditions are not-completed, fault is not currently active and is not causing a DTC light
P2235
Lambda control adaptation at idle, Bank 1 - No signal/communication, test conditions are not-completed, fault is currently active and causing a DTC light
So I'm back at the catalytic converters again which I'm fine with doing, but here are my questions:
1. Do catalytic converters fail this soon on a low mileage vehicle?
2. Why would the P2237/2235 codes come back?
3. Any ideas on what I may be missing? More vacuum leaks, ECM issues, etc?
Lastly as a side note, when changing plugs, I inspected the coils and they all looked fine (i.e. no obvious cracks, wiring in good shape, etc) but I did notice small oil build up on the top of the plugs (none in the cylinders - plugs looked normal). Is that indication of a leaky valve cover gasket and would that be related to any of my issues?
Sorry for the long post - just wanted to be thorough. Any help or insight would be greatly appreciated. Thanks everyone...
