What P20EE means
The SCR catalyst on bank 1 is no longer reducing NOx to the level the ECU expects, even with proper reductant dosing and quality.
How the engine computer detects it
Often the result of catalyst poisoning by sulphur or hydrocarbons, thermal aging, or a leak between the upstream and downstream NOx sensors.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Check engine light on
- Failed emissions inspection
- Possibly slightly increased fuel consumption
- Sulfur (rotten egg) smell from exhaust under load
Common causes
- SCR catalyst aged or poisoned Most likely
- NOx sensor drift Possible
- Exhaust leak between upstream and downstream NOx sensors Less likely
How to diagnose P20EE
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: scr catalyst, nox sensor upstream, nox sensor downstream.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Vehicles that report P20EE most
| Vehicle | Years | Reports | Share | Median miles |
|---|---|---|---|---|
| Ram 1500 | 2014–2017 | 5 | 49k |
Counts of owner complaints to the NHTSA that mention P20EE (13 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.
Reading the code
- P
- Powertrain
- 2
- Generic (SAE) code
- 0EE
- Specific fault
Questions drivers ask
Can I drive with code P20EE?
Usually yes for a short time, if the car drives normally, the temperature gauge reads normal and the check engine light is steady. If the light flashes, the engine loses power or overheats, or other warning lights come on, pull over and have it checked.
Will my car pass an emissions inspection with P20EE?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Will P20EE clear by itself?
The light can go off after several drive cycles without the fault, but the code returns if the cause is still there. After a repair, the readiness monitors need a full drive cycle before an inspection.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.