Flashing Check Engine light

[Bronc3]

Truck ran decent (surprisingly), but had a slew of DTCs. Cleared codes with Forscan, drove a bit until a code returned, found PCM codes (sorry forgot to write them down) for low fuel pressure, misfire #3, and EGR. Fuel filter was plugged, don't think it had ever been changed. Found three different brands spark plugs, one wasn't even the correct plug, SMH. New plugs and wires. Tested EGR valve and made sure it wasn't coked up. New EGR solenoid. Now the truck runs perfect, no codes and the light is out.

 

[franklin2]

Glad to see when doing your own work, you are not afraid to pull the codes and look them up. I have seen many guys that love their trucks, love fuel injection, but refuse to pull codes and see what the computer has to say when they have a problem.

What cable did you use with the Forscan?

 

[19Walt93]

If the light is on it indicates a fault, if it's flashing that means it should not be driven. Just something to keep in mind.

 

[Dirtman]

There is no code for low fuel pressure on a ranger. It's not monitored...

 

[Bronc3]

My Forscan definitely said "low fuel pressure/lean condition, rail #1, bank 1", and went on to suggest possible causes. Top of the list is the fuel filter, but we knew that already.

 

[cbxer55]

Yeah, when my stock fuel pump went bad in late 2016, the only codes I had were P0171 and 174, the lean codes. Nothing else. Put a new pump in, cleared the codes and it's been good since. I have a code now for a "slow" o2 sensor. P0133. Still runs great. No other codes. Will be dealing with that this year once we finally get warmed up around here.

 

[Bronc3]

If the light is on it indicates a fault, if it's flashing that means it should not be driven. Just something to keep in mind.

Yup, read about that, and is why we didn't waste time diagnosing it. Definitely fixed now.

 

[Dirtman]

I'm not saying there is no code that can indicate a possible low fuel pressure issue. Codes are not clear cut pinpoint problem solvers, they can and do often mean any vast number of underlying problems could be causing them. Lean codes on both banks for example can mean low fuel pressure via a failing pump, clogged filter, or bad FPR but they can also be ALOT of other issues causing lean codes. For fuel pressure, there is no physical fuel pressure sensor or any way that the computer can or does monitor fuel pressure so there is no way for the computer to present a "low fuel pressure code". The computer simply knows the designed pressure of 65psi and assumes this is correct when making adjustments to the fuel trims. When those trims cannot produce a proper mixture aka not enough fuel as seen by the oxygen sensors, it sets off a lean code and leaves it to you to figure out why.

 

[franklin2]

You have to remember OBDII was dreamed up by the government, and all car manufacturers where required to adopt it. So the normal run of the mill OBDII codes are just generic codes, not manufacturer specific and may mean different things depending on the manufacturer.

Of course they left a loop hole and let the manufacturers use specific codes also for other systems besides emissions. So that is why you have to pay big bucks to get the transmission, abs and other support system codes. That is what is so great about Forscan, it gives you all those special codes, in addition to the OBDII codes.

 

[Dirtman]

You have to remember OBDII was dreamed up by the government, and all car manufacturers where required to adopt it. So the normal run of the mill OBDII codes are just generic codes, not manufacturer specific and may mean different things depending on the manufacturer.

Of course they left a loop hole and let the manufacturers use specific codes also for other systems besides emissions. So that is why you have to pay big bucks to get the transmission, abs and other support system codes. That is what is so great about Forscan, it gives you all those special codes, in addition to the OBDII codes.

Loop hole? Companies were using computers and "codes" long before the government told them too. "OBD2" is a set standard port and software of monitoring system that fuel injected engines need anyway. Yes the government set the regulations for obd2 but the computers existed and were doing it before then. Obd2 only refers to engine and emission management so any company is welcome to use whatever codes they want for anything else. It has nothing to do with the government.

 

[franklin2]

so any company is welcome to use whatever codes they want for anything else. It has nothing to do with the government.

That's what I call the "loop hole" If you just glance at the whole OBDII thing, you would think the gov is doing the little guy a favor, making the hook-up and the codes standard so everyone can join in and troubleshoot their vehicle. But no, by loop hole I mean the manufacturers didn't go with this theme, and when they could, they made things so the regular guy can't troubleshoot and figure out what's going on without spending big bucks.

If you think about all the smarts in the newer vehicles, they have enough computer power to tell you what's wrong right there as you drive, instead of just a dumb check engine light. But of course we all know their motives, money is the bottom line, I guess it's the American way.

 

[Dirtman]

Well, there is actually a not so sinister reason auto manufacturers don't simply allow the dash to display trouble codes without the use of a tool. Simply put the information provided would be more detrimental than beneficial for 99% of car owners. The less than mechanically inclined amongst us could misinterpret those codes and the information they provide and try to fix it themselves which would likely end very badly. Sorta like how they don't let CVS sell "DIY heart surgery kits"...

 

[Shadowrider6661]

The only problem I have with OBD codes is they don't actually show you what the problem is, they tell you that the problem could be one or more of 'it could be this' ! I'm not sure if I explained that properly, but most of you understand what I mean.

 

[Dirtman]

The only problem I have with OBD codes is they don't actually show you what the problem is, they tell you that the problem could be one or more of 'it could be this' ! I'm not sure if I explained that properly, but most of you understand what I mean.

Yup, the computer can only tell you that a sensor is out of parameter. It can't tell you why. Which again is why manufacturers don't want the general public digging around with codes. For example the screen could give you a p0102 which is a maf sensor low voltage code. So the car owner goes and replaces the maf sensor because the code told them it was bad but the problem persists. In reality the code never said the maf sensor was bad, it told you the PCM was receiving low voltage from the sensor. Joe shmoe doesn't understand you need to test not only the sensor itself but the wiring to it, the PCM, battery voltage, ground straps, etc etc etc.

 

[19Walt93]

The codes are used to start a diag path, the pcm doesn't tell you what's wrong. We had an Autozone 1/4 mile away that would plug their $29 scanner in and sell people all kinds of parts they may not have needed. Instead of codes it would show a readout like "O2 sensor lean" for example. That's not a diagnosis, it's a symptom. By the time we got the customer they were pissed because they'd spent so much without fixing anything and if Autozone hadn't erased the memory we probably had a bunch of erroneous codes to chase that the customer caused while "fixing" it. I purposely didn't track what I spend on tech training, I do remember $5000+ a year for the "value package" that got us paper EVTM's and access to online training and shop manuals. We also had to pay yearly subscription fees for the VCM's.