By on December 11, 2009

OBD, OBdah, life goes on, brah!

TTAC Commentator Detroit-Iron writes:

I have a 2000 Ford Ranger, 2wd 3.0L V6 with 143k miles. The CEL has been on for at least last 70k and I finally went to AutoZone and got the code read. Turns out the O2 sensor is bad and the EGR valve is stuck. Is that the kind of thing that I can fix myself? I don’t want to put a whole lot of money in this truck seeing as it has a lot of miles and has been running reasonably well, if inefficiently (21 mpg all highway), for so long. I have an ok tool set and I do my brakes, but I recently paid $70 to have the fuel filter replaced-I’ve done it before and I didn’t want to do it again. The truck is going back to my parents to be semi-retired and put into “farm use” so I wouldn’t mind fixing it up a little before giving it back but I don’t want to spend a lot.

Sajeev Replies:

No soup for you until you get the actual code from AutoZone! Never, ever throw parts at something: always ask the engine computer what’s wrong, then Google the code for a diagnosis.

Days later, Detroit-Iron replies:

Finally got the code again. It is P1400, it looks like a couple different possibilities ranging from a bad hose to a short. The funny thing is, the first time I got them read (and promptly lost the slips) am pretty sure there were two codes, the other being for a misfire. The print out is as follows:

Definition: BBDPFE ciruit low voltage detected.

Explanation: BBECM detected the EGR pressure sensor (DPFE) voltage below expected values

Probable cause:

BB1.-Failed DPFE sesor (EGR pressure sensor)

BB2.-Open or short circuit condition

BB3.-Sensor hose defective

Sajeev answers:

See, isn’t that much better? Back to your original question: yes, you can fix this yourself. And after your second email, you know where to attack the problem. Let’s not worry about the misfire you may have for now, because the EGR system is your biggest problem.

I had the similar code with my Lincoln Mark VIII, a new DPFE sensor (LINK: http://www.focushacks.com/?modid=80&ht=DPFE%20Sensor%20and%20EGR%20Information) ) fixed the code, it’s usually the fail point on this diagnostic tree. Before you pull the trigger on a new sensor, check the rubber hoses going to/from the DPFE before you buy a new sensor, maybe the vacuum line (BB3, from above) is cracked or rotted. And do a visual on your EGR wiring to make sure that BB2 isn’t the problem.

Bonus! A Piston Slap Nugget of Wisdom:
Don’t cheap out on replacement engine control sensors. Stick with OEM or a name brand like BOSCH or Borg-Warner to ensure you don’t replace this part 12 months from now.

(Send your queries to [email protected])

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20 Comments on “Piston Slap: No OBD-II Code, No Clue Edition...”


  • avatar
    gslippy

    A couple of points:

    1. Check engine lights mean something.  Don’t ignore them for half the life of the vehicle.  If you lived in an area that required emissions testing, it would have been repaired years ago, and the truck’s performance and economy would have been improved all this while.
    2. If the truck is about to be put on the farm, why bother fixing it now?!
    3. If you really want to fix it, it sounds like you are able.  On the other hand, if you’re willing to pay $70 to replace a fuel filter, maybe you ought to have the garage do the job.

  • avatar

    Yes you can do it yourself! The Ranger is one of the best DIY vehicles out there. Don’t worry about the “high” mileage, the vehicle will last 15 years with regular maintenance.

  • avatar
    ExPatBrit

    Sajeev, I couldn’t agree more.  A co-worker replaced the EGR valve because that’s what a parts store said the problem was. I thought it unlikely.
    It didn’t fix the problem, those valves rarely fail, however the DPFE sensors are troublesome and even easier to replace. After I told her what to replace the problem and the CEL went away.
     

  • avatar
    Detroit-Iron

    Thanks everyone.
    @ gslippy, I didn’t pay $70 for a fuel filter, I paid $70 to not get a face full of gas (again).
    @superbadd, all I can say in my defense is that @143k it is still running.

    • 0 avatar
      superbadd75

      I’m glad it’s still running, but an SES light can warn of hundreds of problems. A check engine light indicates that something isn’t right, and something isn’t operating as it’s designed to. Just letting it go forever could potentially cause problems down the road, or mask another problem when it pops up. It’s not a good idea to let an SES light go unchecked, you should repair your vehicle when it needs it. It could save you money down the road.

  • avatar
    Dave Skinner

    Keep in mind, a bad DPFE sensor can cause the PCM to add to much EGR- The bad sensor data can affect the computers ability to measure EGR flow rates.

    Since excessive EGR can cause a misfire, once the system identifies a bad DPFE sensor and disables the EGR valve, the OBD II system may clear the misfire code from memory (or not- lots of variables).

    This is an additional reason to fix problems when the occur. Since a single vehicle fault can “cascade” multiple OBD II codes, fixing problems as they occur keeps  multiple codes from muddying the water. Five OBD II codes may stem from five separate faults, or one problem with multiple symtpoms.

    If you fix ’em when they happen, the troubleshooting stays simple.

  • avatar
    jaydez

    The DPFE sensor is a known problem with the 2000ish Vulcan 3.0L.  Its a very simple fix and not an expensive part.  You can get it cheap from most for parts websites.  I recommend teamfordparts.com.
    I replaced one on my 2000 when it threw the same codes.  It ran 100 time better and the mileage improved… oh, and you wont have as much pinging under load.
    The original design was a metal unit which got too hot a killed the sensor.  The new ones are now plastic.
    Replace it and you will be happy again.  you will need to have the codes cleared though or unplug the battery while you are doing it and it will clear then.

  • avatar
    Don Gammill

    Uh, I wouldn’t go disconnecting the battery to clear codes – that’s always a bad idea because it erases the Keep Alive Memory.
    Erase the KAM and the last few drive cycles worth of data that the ECM uses as a “real-world” average (i.e. taking into accout the vehicle’s mileage and component wear) baseline to determine what sensor readings are truly in or out of range will be gone.
    Once the KAM data is gone, you’ll be back to the factory (i.e. “everything’s brand new”) ranges, which may or may not be realistic given the true state of component wear/how the engine actually runs (and yes, this could possibly trip new codes that don’t represent real problems).
    Bottom line: Always use the scan tool to reset the codes (or, if you’re working on an OBD-I application, follow the manufacturer’s recommendations on clearing codes).

    • 0 avatar
      MBella

      Erasing codes with a scan tool will also erase any learned values. This is the reason a car without all readiness values passed will not pass a state insoection. Actually, on most new cars, disconnecting the battery won’t erase codes.

  • avatar
    Dave Skinner

    “The DPFE sensor is a known problem with the 2000ish Vulcan 3.0L”

    You could replace “2000ish Vulcan 3.0L” with “those Ford products that use it.”

    D/S

  • avatar
    Sammy Hagar

    I have a ’98 Ranger that a few years ago kept throwing a P1401 (high-limit) error.  Researched it a bit online and ended up replacing the DPFE module (Ford has redesigned it a dozen times) and the EGR valve.  Alas, kept getting CEL w/the P1401.
    Eventually I got tired of manually resetting the CEL, so I took it to a real grease-ball garage to troubleshoot.  I wasn’t home but 15 minutes and they called to say that a couple of wires on the DPFE harness connector were loose;  $20 to fix and I’ve been CEL/P1401 free ever since.
    TEST THE HARNESS BEFORE DROPPING $$$ ON EGR VALVES AND FOMOCO DPFE SENSORS!
    Good luck!
     
    Dude, dude, dude, dude, dude… Before you make any purchases (DPFE sensor, EGR valve, etc.), MAKE SURE YOUR WIRING HARNESS AT THE DPFE SENSOR ISN’T DAMAGED! I have ’98 Ranger that kept throwing a 1401 (high limit error); I replaced the DPFE sensor (Ford has redesigned it a dozen times…seriously), the EGR valve,

  • avatar
    Sammy Hagar

    I have a ’98 Ranger that a few years ago kept throwing a P1401 (high-limit) error.  Researched it a bit online and ended up replacing the DPFE module (Ford has redesigned it a dozen times) and the EGR valve.  Alas, kept getting CEL w/the P1401.
    Eventually I got tired of manually resetting the CEL, so I took it to a real grease-ball garage to troubleshoot.  I wasn’t home but 15 minutes and they called to say that a couple of wires on the DPFE harness connector were loose;  $20 to fix and I’ve been CEL/P1401 free ever since.
    TEST THE HARNESS BEFORE DROPPING $$$ ON EGR VALVES AND FOMOCO DPFE SENSORS!
    Good luck!

  • avatar
    Mike999

    This is the perfect example of why we should be running ELECTRIC Motors.
    There are no O2 sensors, or EGR’s.
    There’s no engine, transmission, exhaust system,…
    EV’s won’t be perfect, but, their sheer drop in parts count will make them less expensive to own.
     

    • 0 avatar
      Robert.Walter

      Until you have to buy a new battery…

    • 0 avatar
      John Horner

      We shall see about that. Electronics modules are notoriously expensive for autos and those battery packs are going to sucker punch you when the finally need to be replaced. Last year we looked at a Fusion Hybrid (nice vehicle, by the way), but I also asked what the cost would be to replace the battery pack out of warranty if needed some day. The salesperson said “I’ll check”. She went back to the service dept. and came back with the grim news: $7,000 parts plus and hour or two of labor. Ouch.

      Mind you, this is just the relatively small battery pack for a hybrid, not the massive unit required for a true electric car.
       

  • avatar
    Andy D

    Generic advice.  To de- pressurize a fuel system for service. Start  the   engine,  remove  the  fuel  pump fuse. When  engine  stalls, turn off  key.  Always, just ” crack”  a pressurized fitting  to   let it  bleed.

    • 0 avatar

      Sometimes pulling the fuse doesn’t do a damn thing.  Learned that the hard way with a Mondeo-Cougar, and I couldn’t find the fuel pump shut off switch either.  The best way is to let the car sit overnight and crack it open before you put the key in the ignition.
      Fuel systems (maybe not on direct injection systems) lose all their pressure overnight, hence the reason for the fuel pump whine you sometimes hear when you turn the key on. Wear rubber gloves before you get under the car and you may not get any gas on your skin too. Easy.

    • 0 avatar
      rocketrodeo

      Specific advice: there’s a fuel pump switch above the passenger side kick panel. No fuse pulling required.  I’ve never even had a drip replacing the fuel filter. Unfortunately, it’s an expensive  filter. The replacement part is an aluminum canister clipped into a steel bracket that bolts to the frame as an assembly, and replaces the original one-piece rotomolded plastic filter. I have yet to find a p/n for just the canister.

      2000 model Ranger w/ Vulcan and 5-speed, 130K and the most trouble free vehicle I have ever owned, including three hondas, two acuras, two toyotas, and two nissans; there is something to be said for decade-plus production runs. As the OBD port is currently occupied by a ScangaugeII, I’ll know pretty instantaneously what a CEL indicates, should the truck ever throw one. It hasn’t yet.

  • avatar
    RogerB34

    Change out the two upstream O2 sensors.  Bosch for about $50 each Standard for $42 each.  EGR valve is about $40.  Way past their lifetime.  Check for access, use a little penetrant on just warm exhaust.  O2 socket will cost about $10. 

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