Often times mentioning Diesel Exhaust Fluid(DEF) to a diesel owner will bring a solemn look to their face. DEF is probably a little more frustrating to Duramax owners due its inconvenient DEF tank fill location and common reductant tank heater issues. This article will take a look at the duramax reductant tank heater issues that are most common and advise the best repair.
Simply put, the reductant tank heater refers to the heater that keeps the DEF or reductant warm when temperatures are below freezing. The reductant, which is a reducing agent, helps reduce oxides of nitrogen(NOx) within the diesel exhaust after treatment system.
Common Reductant Tank Heater Issues
The reductant tank heater operates along with other reductant heaters when temperatures drop below freezing and depending on the location, may never happen. Most owners will first find their reductant tank heater is out of specification by a check engine light. By using a code reader the most common code is P20B9, DEF reservoir heater control open circuit/low voltage.
The most common repair for the P20B9 code is either replacing or manually engaging the reductant tank heater. Starting with the latter, manually engaging the tank heater requires a special scanner. Often times these scanners are very expensive so most consumers would be better off inquiring with a local diesel mechanic shop. Manually engaging the tank heater allows sensors to read that the heater is functional and in good working order. If this test fails to remove the P20B9 code then the next most common repair is replacing the reductant tank heater.
The best price we found at the time of writing this article was Amazon, check now!
The procedure to replace the tank heater is the same for Duramax trucks from 2011-2016 as the location was unchanged.
- The DEF tank will need to be dropped for easiest access as the tank heater will be removed from the top of the tank.
- There are two straps that secure the tank in place, both will need to be removed.
- Support the tank with a jack or other suitable device to ensure it does not fall.
- Once dropped, the tank heater is located under the pump centrally located on the top of the tank.
- There are a series of wires and connectors that will need to be disconnected and placed to the side.
- Remove the upper part(pump) before removing tank heater. This will allow easier maneuverability.
- The retaining ring that holds the heater in place twist off and will likely need a hammer screwdriver to apply the initial force to get the ring moving.
- Once the ring is removed, pull out the heater assembly being careful not to allow any debris in the tank.
- Reinstall in reverse order.
This repair, if done one your own will require 1-2 hours for repair and necessary tools.