The EFI computer has two ways to cypher how much fuel to inject into the engine. First is to use an assortment of sensors, the map/maf, throttle position, engine coolant temp, rpm, intake air temp. That is the only information carbureted engines have access, to set the air/fuel mixture, and they can run ok. So too can an EFI engine. In fact it only uses that set of information to start the engine and run it the first few minutes. EFI engines have a second source of info, the o2 sensor. the o2 sensor takes a few minutes to start working, but once it does, EFI engines uses the first set of sensors to get the air/fuel mixture approximately correct, then the o2 sensor to fine tune.
I have no way of knowing what’s causing your dash warning light of course. But if you’ll allow a speculation, say the computer – monitoring the o2 sensor – finds it has to pulse the injectors much more or less than it thinks it should have to based on the first set of sensors. That would confuse it and could trigger this problem. So you probably are looking at a problem from among
- faulty o2 sensor
- faulty map/maf sensor
- faulty throttle position sensor
- fuel pressure problem
- faulty coolant temp sensor or intake air temp sensor
- ignition system problem
- compression problem
- deferred maintenance problem, engine air filter, fuel filter, spark plugs, s.p. wires, distributor cap & rotor.
Rather than testing them all one by one, that’s what the diagnostic software build into the engine computer is for, to provide a diagnostic code and a clue where to start.