Does Diesel Exhaust Fluid (DEF) Expire?
3 Answers
Diesel Exhaust Fluid (DEF) can expire. Here is some additional information: 1. How to determine if it has expired: The quality of DEF is significantly affected by temperature. If the storage temperature exceeds 35°C, it is prone to deterioration. A simple trick to check if DEF has expired is to smell it. At high temperatures, DEF decomposes and releases ammonia gas (ammonia is produced when urea breaks down), which has a pungent odor. Therefore, you can determine if DEF has expired by its smell. 2. Hazards of expired DEF: When DEF is exposed to heat, its normal components evaporate as ammonia gas, reducing its purity. As a vehicle exhaust treatment fluid, its reducing ability is also diminished. Using expired DEF may result in insufficient exhaust gas reduction, leading to environmental pollution. Therefore, it is essential to perform simple checks to ensure the effectiveness of DEF before use.
Automotive urea does expire, and I've learned this the hard way. Last time, I found a stored barrel in the garage, and upon opening it, I discovered it had crystallized into white solids. Generally, urea has a shelf life of about 18 months, but it decomposes even faster if stored in poor conditions, especially under high temperatures and direct sunlight. Impurity deposits can clog the injector nozzles, and repairing the SCR system can cost several thousand dollars. Now, I've made it a habit to mark the purchase date on the barrel with a marker pen and store it in a cool, dry place. In summer, it's best to buy smaller packages and use them within three months for safety. When replacing the urea, it's also a good idea to check the filter screen of the storage tank—don't wait until the fault light comes on to regret it.
Vehicle urea, like milk, has a shelf life and can easily deteriorate if stored improperly. I've seen many cases in auto repair shops where owners bought large barrels of urea to save money, only to trigger SCR system alarms after six months of use. Diagnosis revealed urea crystallization clogging the nozzles. Reputable brands typically indicate a shelf life of 12 to 24 months, but never store it in the trunk exposed to direct sunlight. High temperatures can cause urea to decompose into ammonium salts, forming sediments. Recommended storage temperature should not exceed 25°C, and opened containers are best used within 6 months. Periodically check the urea solution condition - replace immediately if it appears cloudy or contains impurities. For diesel vehicles, using fresh urea is both a way to protect the vehicle and save money in the long run.
