Mexican Diesel Fuel/Sulfur Effects Update
Much to my distress I just learned here in the Southern Baja that the owner of a late model GM diesel pickup paid almost $3,000 to ship his truck back to the USA when it went into limp mode (5 mph) in...
Forum Discussion
BriannSue, I have one of those "laptop computers", which is a sophisticated code reader and systems monitor that uses manufacturer's proprietary software to monitor and analyze an enormous amount of systems data from the ECM (on board computer).
Some of the data is "real time", which means that it is simply a momentary snapshot of something like MAF, or Mass Air Flow, which is the amount of air entering the engine per second. It is possible to record the data if the "laptop" stays hooked up, but that real time data is lost if a recording device is not actually attached. This means that some occurences are never recorded, particularly if they fall within normal parameters.
In addition to real time data, codes may be triggered when a monitored system moves out of spec, such as the codes P20EE and P2BAD I've already mentioned. There are, however, two types of codes. One type automatically erases when a system returns to normal, and P20EE is an example. Other codes, like P2BAD, require not only the system to return to normal, but a series of subsequent montitorings to be correct, and/or technician intervention to reset the code. This is so that important codes can not be erased accidentally or deliberately by owners using a simple code reader. These codes are retained because they MIGHT indicate a serious issue which should be investigated.
In field situations like the ones I deal with in Mexico, the engine light will come on when a P20EE code is triggered by out of spec NOX readings in the exhaust downstream from the SCR/DOC. If a regeneration occurs fairly quickly after the code is triggered, simply because it has become due as a result of the kms/miles traveled, the P20EE code will be erased automatically, and the engine light will go out by itself, once the regeneration has finished. This is because NOX emissions control returns to normal after sulfur compounds are burned out of the SCR by the regeneration cycle.
If a regeneration does not occur within a set number of NOX monitoring cycles after a P20EE code is generated, a second code, P2BAD, will be generated, because the system now assumes that the Diesel Exhaust Fluid is bad. The P2BAD code does NOT automatically erase, even after a regeneration. Technical intervention is required. This is so that a record is maintained for investigation by a technician, but as previously mentioned, a P2BAD code can be triggered by many different situations, so it is not generally considered important unless there is an obvious condition causing the P2BAD code. Past use of higher sulfur fuel is NOT an obvious condition, and is not recorded by any system. A fuel sample would have to be sent to a laboratory to determine what level of sulfur it contains.
When I assist owners who have both a P20EE and P2BAD code while in Mexico, I use my "laptop" to force a driving regeneration to clear out the sulfur compounds. I can then use my "laptop" to erase the P2BAD code, so at the end of the process there is NO REMAINING RECORD of the incident, and all systems return to normal. It is also important to note that the combined P20EE/P2BAD situation occurs ONLY on 2013 and later GM products. No other model years or makes experience any permanent codes as a result of using Mexican diesel, so most owners will never notice anything unusual while driving in Mexico.
Although I am based on the Baja, I have trained and equipped 4 other Snowbirds on the Mainland, so that they can perform the same service for stranded owners. I took the step of training others after having been flown by stranded owners to other parts of Mexico last season to carry out the service. Even though my costs were paid, I prefer not to be spending time flying around Mexico to do this work.
Bottom line again is, if you learn of an owner who needs assistance, please put him or her in touch with me and I, or one of the other properly equipped people on the Mainland, will imediately provide help. No record of what has happened will remain in the vehicle database, PERIOD.
Some of the data is "real time", which means that it is simply a momentary snapshot of something like MAF, or Mass Air Flow, which is the amount of air entering the engine per second. It is possible to record the data if the "laptop" stays hooked up, but that real time data is lost if a recording device is not actually attached. This means that some occurences are never recorded, particularly if they fall within normal parameters.
In addition to real time data, codes may be triggered when a monitored system moves out of spec, such as the codes P20EE and P2BAD I've already mentioned. There are, however, two types of codes. One type automatically erases when a system returns to normal, and P20EE is an example. Other codes, like P2BAD, require not only the system to return to normal, but a series of subsequent montitorings to be correct, and/or technician intervention to reset the code. This is so that important codes can not be erased accidentally or deliberately by owners using a simple code reader. These codes are retained because they MIGHT indicate a serious issue which should be investigated.
In field situations like the ones I deal with in Mexico, the engine light will come on when a P20EE code is triggered by out of spec NOX readings in the exhaust downstream from the SCR/DOC. If a regeneration occurs fairly quickly after the code is triggered, simply because it has become due as a result of the kms/miles traveled, the P20EE code will be erased automatically, and the engine light will go out by itself, once the regeneration has finished. This is because NOX emissions control returns to normal after sulfur compounds are burned out of the SCR by the regeneration cycle.
If a regeneration does not occur within a set number of NOX monitoring cycles after a P20EE code is generated, a second code, P2BAD, will be generated, because the system now assumes that the Diesel Exhaust Fluid is bad. The P2BAD code does NOT automatically erase, even after a regeneration. Technical intervention is required. This is so that a record is maintained for investigation by a technician, but as previously mentioned, a P2BAD code can be triggered by many different situations, so it is not generally considered important unless there is an obvious condition causing the P2BAD code. Past use of higher sulfur fuel is NOT an obvious condition, and is not recorded by any system. A fuel sample would have to be sent to a laboratory to determine what level of sulfur it contains.
When I assist owners who have both a P20EE and P2BAD code while in Mexico, I use my "laptop" to force a driving regeneration to clear out the sulfur compounds. I can then use my "laptop" to erase the P2BAD code, so at the end of the process there is NO REMAINING RECORD of the incident, and all systems return to normal. It is also important to note that the combined P20EE/P2BAD situation occurs ONLY on 2013 and later GM products. No other model years or makes experience any permanent codes as a result of using Mexican diesel, so most owners will never notice anything unusual while driving in Mexico.
Although I am based on the Baja, I have trained and equipped 4 other Snowbirds on the Mainland, so that they can perform the same service for stranded owners. I took the step of training others after having been flown by stranded owners to other parts of Mexico last season to carry out the service. Even though my costs were paid, I prefer not to be spending time flying around Mexico to do this work.
Bottom line again is, if you learn of an owner who needs assistance, please put him or her in touch with me and I, or one of the other properly equipped people on the Mainland, will imediately provide help. No record of what has happened will remain in the vehicle database, PERIOD.
