This testing engine code means the cylinder fuel  injection circuit has a malfunction. It may look formidable but if you got the vehicle’s troubleshooting diagnostic tree, it should be easy for you. Shown below is a sample diagnostic tree that you can use and study. All the confusing terms here are available at ATS as shown:

Here are the basics testing engine code procedures available to you:

Basic vacuum leaks testing

You can do this by using a carb cleaner or a bottle of water mist spray. When directed at the engine vacuum leak, the engine rpm will change pointing to a vacuum leak.

Basic exhaust manifold exhaust test procedures

You can connect a pressure gauge in the engine exhaust and observe the engine pressure reading when the engine rpm is rev up. Higher pressure reading usually indicates blockage in the exhaust system like your catalytic converters or mufflers.

Testing oxygen sensors using your DVOM

Observing oxygen sensor voltage readings when the engine is running can give you an indication if the sensor is good or not. You can determine this by following the suggested voltage readings by the vehicle manufacturer.

EVAP system checking canister purge solenoids

The Evap purge solenoids can be traced and tested for integrity such as mechanical operation and electrical circuitry. Again you need to follow the service manual or wiring diagram for testing guides.

Testing fuel injectors for resistance and spray patterns

Using a digital voltmeter, you can measure the injector coil resistance readings as recommended. A ground test can be done as well to determine if the coil is shorted. Finally, if all readings are OK, the injector can be tested in a fuel bench tester to determine the injector spray pattern and any signs of fuel flow blockage.

Testing fuel pressure regulator vacuum pressure and common problems

The fuel regulator can be tested for the presence of vacuum at the vacuum hose connections. At the same time, if the hose itself has the smell of fuel, it shows the fuel regulator diaphragm is damaged.

When testing engine code for P0201 basics are all done, you can decide to either repair or replace the defective fuel components. Don’t forget to reset the P0201 after each repair. An online mechanic at ATS can assist you do it so it can be done properly without replacing unnecessary parts.

In the end, testing engine code is easy if you use the correct information.

Thanks!