1999 Honda Passport how to fix trouble codes P0171 -P0171 -

Codes P0171 and P0174 indicate Bank 1 and Bank 2 are running lean. Suspect faulty oxygen sensors located underneath vehicle on exhaust system. Also inspect MAF (Mass Airflow) sensor.

Code P0304 indicate a cylinder 4 misfire detection. Need to inspect your spark plugs to ensure all cylinders are getting proper spark.



Post results and I will follow up.



Thanks for using 2CarPros.com!

HI i HAVE 99 HONDA PASSPORT AND i GET TROUBLE CODE P0304 i KNOW THAT THIS MEAN CILYNDER MISFIRE DETECTED i CHANGE THE SPARK PLUGS , COIL AND STILL GETTING THIS CODE ANY IDEAS? COULD BE THE FUEL INJECTOR SOUND LIKE IS WORKING SO I REAL CONFUSE. THANKS FOR YOU HELP

Does that cylinder get good healthy spark to the plug? Check fuel pressure at the rail as well.









Thanks for using 2CarPros.com!

yes the spark plugs are getting good spark how can make sure that the injector is working properly thanks

First just use a manual fuel gage to check pressure at the rail. If there isn't enough fuel pressure then the injectors wont receive fuel to burn. If OK here, test the injectors to see if they are getting signal to pulse. You can also use a mechanic stethoscope to listen to the injectors. You should be able to hear each one clicking with someone cranking engine or if engine will start, with engine running.









Thanks for using 2CarPros.com!

thanks for all you help , the injectors are working fine I can heart it. but cant get fuel pressure tester is any way the check the fuel pressure without tester.

Ok. So plugs, wires, injectors all check out OK. We'll hold off on fuel pressure gauge for now. Check for vacuum hose splits, kinks or improper connections. Also check intake manifold for vacuum leak. You said the coils were good as well, so did you measure resistance? It should be 2.6 - 2.7 k/ohms. If it isn't then the ignition control module may be faulty.