Contaminants-in-Diesel Exhaust Fluid Diagnosis

CONTAMINANTS-IN-DIESEL EXHAUST FLUID DIAGNOSIS
(Vehicles With VIN L, RPO LGH Only)

Description

Maximum oxides of nitrogen (NOx) reduction efficiency of the Selective Catalyst Reduction (SCR) system requires the supply of diesel exhaust fluid (DEF) or reductant. Consisting of a mixture of 32.5 % urea and 67.5 % deionized water, fresh DEF should be clear in color with just a slight ammonia smell. DEF designed for SCR systems should carry one or more of the following international certifications:

* DIN70700
* ISO 22241-1
* American Petroleum Institute (API) Certification

Inspecting for Contaminates

While contamination may result from any number of fluids, it's more likely that contamination will involve one the following common automotive fluids. As clean DEF is clear, contamination by any of the these fluids will cause the DEF to exhibit a trace of color associated with a specific contaminate.

* Windshield washer solvent - blue
* Engine coolant - orange or green
* Engine oil - brown
* Transmission fluid - red or brown
* Diesel fuel - brown

Reference Information
Description and Operation

Exhaust Aftertreatment System Description. Emission Control Systems
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information
Special Tools

J 26568 Coolant and Battery Fluid Tester

Circuit/System Testing

1. Collect a DEF sample of about 150 ml (5 oz) from the DEF tank in a clear container.
2. Observe the DEF sample. The DEF sample should be clear with no obvious coloration when held up to a light.

• If the sample is not clear, replace the DEF tank assembly.

3. Observe the DEF sample. The DEF sample should be odorless or have a slight ammonia smell.

• If the sample has a strong ammonia smell, drain the remaining DEF and refill the tank with fresh DEF.

4. Measure the specific gravity or freeze point of the DEF sample using the J 26568. The specific gravity of pure DEF should be greater than 1.315 or the freeze point between -32 to -34°C (-27 to -29°F).

• If not within the specified range, drain the remaining DEF and refill the tank with fresh DEF.

5. If the DEF tests normal, perform the DEF Quality test with a scan tool. The DEF Quality test should pass.

• If the test fails, replace the DEF.

Repair Instructions

Perform the Diagnostic Diagnostic Repair Verification (Verification Tests) after completing the repair.

Emission Reduction Fluid Tank Replacement (Emission Reduction Fluid Tank Replacement)