How serious is this DTC?
As with most EVAP faults, I would say it’s low on the severity scale. The entire system was primarily designed to reduce emissions into the atmosphere. Obviously, it does much more in the meantime, but all that said, really the only thing negatively affected by this fault is the atmosphere. For now, I can’t think of any EVAP system issue that could harm the overall safety of the vehicle. This does NOT mean you can keep driving the vehicle day after day without addressing the problem. One problem always leads to another if not resolved for too long.
What are some of the symptoms of the code?
Symptoms of a P2028 trouble code may include:
- State/provincial emissions test failure
- Check Engine Light (CEL) on
- Slight decrease in fuel efficiency
- Fuel odor
- Possible abnormal fuel filling symptoms (long fill times, unable to fully pull the gas pump trigger, etc.)
What are some common causes of the code?
Causes of this P2028 fuel compensation code may include:
- Faulty EVAP fuel vapor temperature sensor
- Broken or damaged EVAP fuel vapor temperature sensor wiring harness
- Inconsistent electrical connection, e.g., fuse not properly installed in designated slot, loose connector pin, broken tab on connector, etc.
- Short circuit in the power wire
- Excessive resistance in the circuit
- ECM (Engine Control Module) issue
- Pin/connector problem (corrosion, melting, broken locking tab, etc.)
How to troubleshoot and repair a P2028 code?
As mentioned above, the overall health of the EVAP (Evaporative Emissions) system is of great importance. Check that the involved components are not clogged and that there are no visible cracks in the plastic pipes. It would be a good idea to locate where the EVAP system gets its fresh atmospheric air to introduce into the system to regulate pressure differences. In some cases, most parts used in this system will be located under the vehicle. I would recommend using wheel ramps rather than a hydraulic jack for their convenience and, most importantly, safety benefits.
NOTE: Be careful when disconnecting/handling EVAP hoses and pipes. Often, they may seem fine until you try to disconnect them and a clip or the entire hose breaks, and now you have to replace/repair something to proceed with your diagnostics. Be extremely careful here.
Test the sensor. From my experience, the ECM uses the voltage readings from the EVAP fuel vapor temperature sensor to monitor temperatures. That said, there is most likely a specific pin test that can be performed to check the sensor’s functionality.