How Severe Is This DTC?
A stored P202C code should be considered severe and addressed as quickly as possible. The SCR system could be disabled because of this. Catalyst damage could occur if the conditions that contributed to the code being stored are not corrected in a timely manner.
What Are Some of the Symptoms of the Code?
Symptoms of a P202C trouble code may include:
- Reduced fuel efficiency
- Excessive black smoke from the vehicle’s exhaust
- Decreased engine performance
- Other SCR-related codes
What Are Some Common Causes of the Code?
Causes of this code may include:
- Faulty reductant tank heater element
- Open or shorted circuits in the reductant tank heater control
- Faulty SCR controller/PCM or programming error
What Are the P202C Troubleshooting Steps?
A diagnostic scanner, digital volt/ohmmeter (DVOM), and vehicle-specific diagnostic information source will be needed to diagnose a P202C code.
You can use your vehicle information source to locate a technical service bulletin (TSB) that matches the vehicle’s year, make, and model; as well as engine size, stored codes, and presented symptoms. If you find one, it could provide helpful diagnostic information.
Use the scanner (connected to the vehicle’s diagnostic connector) to retrieve all stored codes and relevant freeze frame data. It’s a good idea to record this information before clearing the codes, then test drive the vehicle until the PCM enters readiness mode or the code resets.
If the PCM enters readiness mode at that point, the code is intermittent and may be much harder to diagnose. If this is the case, the conditions that contributed to the code being stored may need to worsen before an accurate diagnosis can be made.
If the code immediately resets, the next step in your diagnosis will require you to search your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, and component testing procedures/specifications.
Step 1
Use the DVOM to test the reductant tank heater element according to manufacturer specifications. Heaters are typically blanket or pin type. Heating elements that do not test within allowable maximum parameters should be considered faulty.
Step 2
Use your vehicle diagnostic information source and the DVOM to test the reductant heater circuit voltage (typically battery voltage) with the system activated. If current conditions don’t allow activation, use the scanner to manually activate the heater.
Step 3
If the reductant tank heater is functional, use the DVOM to test the input and output signal circuits from the fuse panel, PCM, and ignition switch. Disconnect all controllers before using the DVOM for testing.
Reductant tank heater systems are used exclusively in diesel-powered vehicles and in colder climates