This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.
NOx Trap Efficiency Below Threshold Bank 1
Vehicle ECMs code a P2000 when they detect a malfunction with the NOx Trap (Nitrous Oxides Absorber Trap). This device, found on lean-burn gasoline and diesel engines, is placed downstream of the engine exhaust manifold and converts harmful nitrous oxides into harmless nitrogen before it’s released back into the exhaust. The ECM sets the P2000 trouble code when the NOx trap has efficiency reads below the emissions standards threshold on Bank 1. The Check Engine Light will illuminate to notify the driver that there’s a problem.
The typical causes for P2000 are fairly easy to diagnose, and the potential time and cost for correcting these issues varies. Here’s what usually causes the issue:
- The catalytic converter has failed.
- The wiring harness has an open or short circuit
- Connectors are loose or damaged
- ECM has failed or is failing
- The NOx trap sensor or solenoid is damaged or broken
Most of the time this trouble code doesn’t have any readily apparent symptoms. Other than the Check Engine Light, you may not notice anything wrong while driving. Occasionally, depending on the cause, the Check Engine Light may flash on and off.
You need to follow a step-by-step diagnosis protocol to make sure you don’t overlook the problem or replace perfectly good parts. Here’s how to troubleshoot a P2000:
- Use a scan tool to check for any codes stored in the vehicle's ECM. That means pending codes, too. Take a snapshot of the freeze-frame data for each code to verify conditions when each code was set.
- Clear the codes and take the vehicle for a test drive. Try to recreate the conditions of the original code if possible.
- Make a thorough visual inspection for any damaged wires, connectors, sensors or components around the NOx trap.
- Check and test the catalytic converter for physical damage and blockage or clogging. Sometimes rust or road hazards create pinholes or other damage that cause catalytic converter malfunctions.
- Verify that sensor and solenoid readings are within normal limits with the OBD-II scanner.
- Test the ECM to verify it’s functioning correctly. A bad ECM is a rare occurrence for most vehicles, but it can happen.
Like any diagnostic process, don’t skip any steps. Clearing codes to see if they recur, checking wiring harnesses/connectors and searching for physically damaged components are critical to an accurate diagnosis. You need the correct diagnosis the first time if you want to fix the problem yourself the first time without spending time and money needlessly.
How serious is this?
Your vehicle will most likely run fine even when a P2000 code has been set by the ECM. This trouble code may not cause your care to stop running, but it will not pass emissions tests until the issue is corrected.
What repairs can fix the code?
These are the most common repairs to clear a P2000 trouble code:
- Replacing your vehicle’s ECM (expensive and time-consuming)
- Replacing the catalytic converter (also expensive and time-consuming)
- Repairing or replacing a wiring harness (a cheap and easy fix)
- Fixing poor electrical connections (another cheap and easy fix)
- Replacing a failed sensor or solenoid (cost depends on what sensor or solenoid needs replacement, and it can be complicated to replace depending on the vehicle)
You probably aren’t going to pull this trouble code and need it fixed right away. If your vehicle is due for safety and emissions inspection, you will need to correct this issue before it will pass the emissions test. If you have an OBD-II scanner and you think you can do the work yourself, go for it. If not, have a professional diagnose and repair your vehicle so it can pass emissions.