High Quality Common Rail Fuel Injector Nozzle DLLA142P1709 0433172047 for Denso Nozzle

So your engine is running badly (or not at all).  What’s the next step in diagnosing a problem with the engine injectors?

Call A Mechanic

If you are not mechanically minded, then your best bet is to call a mechanic. Injectors (and engines) can be complicated and expensive to repair, so if you are unsure at all, then let an expert diagnose it.

Hook Up An OBD Code Reader

This will tell you if the Engine Control Unit (ECU) has logged any errors. If an engine misfires because of a bad injector, there will be an error code that will point to the injector in question. If you are using a generic (not vehicle manufacturer specific) code reader then you can expect to see codes beginning with P02. For example, a fault with an injector in cylinder one would give a code of P0201. You may also see other error codes such as P0101, P0300, P0299.

Visually Inspect The Engine Bay

If you open up the hood and there is a strong smell of fuel then a leaky injector could be the culprit. If there are no error codes, the next step will be to remove each injector for inspection. This is usually best left to fuel injector experts.

Remove And Test All Injectors

Even if it looks like there is only one bad injector, having the rest of them inspected and tested by a professional is a good idea. If the engine has covered a lot of mileage, chances are the other injectors are dirty and may fail soon too.

If you suspect that a broken injector is your problem, then the easiest way to diagnose it is to check the engine ECU for error codes. A broken injector will cause an engine to misfire and this will trigger an error code.