Special offer for F series users. Satisfied or your money back!*
*even if NOXEM was installed, refund up to 419.00 EUR (customer pays for Online diagnostics only)
Terms and conditions
Applies: within 3 months after purchase of NOXEM 402
The customer receives a refund if:
12C401 error appears, and Online diagnostics confirm reduced efficiency of CO converters (customer eliminated all other issues: problems with injectors, ignition, etc.), and the customer decided not to use NOXEM.
The customer provides all diagnostics data requested for Online diagnostics (data reported by INPA, list here + misfire counters and other specific information, if requested by Bimmerprofs) and follows Bimmerprofs recommendations.
Refund is sent within 3 working days after receiving NOXEM 402 back. Shipping costs back to Bimmerprofs are covered by the customer. Amount of refund: 419.00 EUR if the returned item is in mint condition; 350.00 EUR if the probe is clogged/damaged; up to 200.00 EUR if the probe is damaged and the device has signs of use (scratches, etc.).
Background
Nowadays (in 2025), most F10/F11 with N53 series engines have hidden problems (more about hiding of problems read here and here) with CO and NOx converters. Reduced efficiency of CO converters results in disabled Stratified charge and later: 12C401 error (if NOXEM 402 is installed) – DME notices lowered the amount of nitrites, reported by NOx sensor (DME ‘’understands’’ that the amount of nitrites in Homogeneous injection should be relatively high because of damaged CO converters). More about this can be read here.
Recommended strategy
We recommend NOXEM 402 as the best available solution for the F series with the N53 series engine. With NOXEM 402:
You can renew the Stratified charge as the primary injection method if the remaining systems (except the NOx converter) are in working condition. Or – Stratified charge is renewed for a limited time: requires periodical deleting of errors (even if NOx converter is aged/damaged and CO converters have reduced efficiency);
You can skip real desulfation sessions (just perform re-adaptation using INPA within 5..10 minutes);
Even if CO converters have significantly reduced efficiency, Stratified charge can be restored for at least 400..700km within seconds simply by deleting errors (deleting errors clears performance test counters for CO converters, too). Deleting errors 3..4 times per year typically is enough to re-measure injectors and restore correct adaptations and fuel mixture.
Note: real desulfation sessions (if OEM NOx sensor is installed) are not available if DME identifies significantly lowered efficiency of NOx converter and/or lower efficiency of CO converters. Errors about lowered efficiency of NOx converter (if) are stored in the Info list (available only in INPA; not available in ISTA and 3rd party tools), and errors relating to reduced efficiency of CO converters typically are not stored at all (these errors appear only if/when the efficiency of CO converters drop below 5..10% of initial value).
Notes for TUV/TI
If the car has hidden problems with reduced efficiency of CO converters (the only error stored is 12C401; all other issues are fixed), delete errors 100..300km before emission tests. Warm up the engine and CO converters right before tests (drive your car more aggressively than usual for at least 10..20km). If there are no other issues, the vehicle will pass emission tests in both (Stratified charge and Homogeneous, depending on DME choice) injection methods.
If problems with CO converters are critical (if the efficiency of CO converters drops almost to 0, in this situation, DME records errors about their efficiency), your car will not pass emission tests in Homogeneous injection, and both HC and CO readings will be increased. In this case, the only solution is: the temporary forced activation of a Stratified charge. To do this: delete errors right before emission tests. If there are no other issues, DME will re-enable the Stratified charge for some time (it depends on the remaining capacity of CO converters), and you will be able to pass emission tests (both HC and CO are low in Stratified charge even with non-working CO converters).
Note: don’t forget to prepare/print papers about increased Lambda readings during emission tests! Read more here.
