If the cause of the defect is detected – injector(s), the user of the car very often has a dilemma. Dealer and large service centers very often suggest replacing all injectors. Why is that? Is it the best solution?

Why do dealers offer to replace all in injectors?


1. Lack of information

As already mentioned in several entries, dealers are not allowed to use INPA. With ISTA D/+ following information regarding parameters of injectors is not available:

  • ../F5/Shift+F6/F1 live data, opening time and multiplicative adaptations for each injector. Indicate flow-rate of injectors in the exact conditions;
  • ../F5/Shift+F6/F1 data of electric charge. They display “health state” of a piezo element of the injector;
  • ../F5/Shift+F6/F2 learnbits. Indicates, which injector tests are completed, which still has to be performed;
  • ../F5/Shift+F6/F3 results of chemical tests of injectors. Indicates “flowing” of injector parameters in the conditions of low, average and high load;
  • ../F5/Shift+F6/F4 indicates the behavior of injectors (by banks) in lower temperatures;
  • ../F5/Shift+F6/F5 indicates “health state” in idle, for Stratified charge mode. This has both references and live data values for this mode.

Using ISTA D/+, the specialist even doesn’t sees multiplicative type LTFT for banks regarding MSV/MSD management units (they indicate injector problems in average load conditions within the bank), BMW doesn’t gives any explanation regarding Rough run data – their usage in dealer centers is limited with “something is wrong”.

A dealer is not allowed to use the ELM327 adapter, which allows reading misfire counters in OBD 6 mode. Accordingly – it’s not possible to identify cylinder, which has misfires (leaking injector can be one of the causes of misfires, and also cause of incorrect Rough run data).

Without this and a series of other information, the specialist of BMW dealer center specialist is completely “blind”. In no way, he can identify the damaged injector. Unfortunately, the error messages regarding misfires (the only one available information), recorded in the error message memory of DME very often don’t indicate the damaged injector, but the “healthy” one. The cause is very simple – damaged (leaking) injector pushes to reduce fuel amount for whole bank, as a result – in another cylinder (with good injector) misfires start to appear, because the fuel mixture becomes very lean. Accordingly – the error message actually indicates the good injector!


2. Profit as a criteria

The task of BMW dealer center (and any other service center) is to have profit, not to save money of the customer. For example, selling 6, not only one injector, not only EUR 70 will be earned, but 6 times more: EUR 420. Additionally, the time will be spared. A specialist will perform a routine task, not – replace one injector, perform test drive, re-adapt the engine, repeated check-up, etc. I doubt, that the dealer, for example, will wait till next day’s morning to try a cold start and try to understand, which injector is leaking. Many other cars are waiting “in line”! Replacing all injectors, the repair institution will earn 5 times more, in addition – during 2 .. 3 times shorter period!


3. Lack of specialists

Unfortunately,  mentioned above regarding priorities in the performance of service centers demotivates specialists, who work there. If they regularly hear “don’t make the science here, but earn money”, a talented specialist usually chose to work privately or break down and start to follow the instructions of management. This allegation is based on my personal experience in my region of residence, but I think, that the situation elsewhere is similar.


Of course, everyone chooses the most beneficial scenario of repair. I don’t think, that due to one leaking injector (possible typical defect – micro-part, stuck in the injector) all injectors have to be replaced. With addendum – if the diagnostics specialist is able to identify the damaged injector!