Dreaded Engine Light- what now? Code P0471

[Desert Sage]

Engine light went on- Code reader says it's P0471. I tried to clear the Code (Blue Driver), but it cannot be erased because the code is "permanent," but the dash light did go off.

I can't figure out what the code means- seems like anything from a EGR to a leaky head gasket. Prior to the code, there were no symptoms. 49K on the Ranger- never been in a shop- always do maintenance (oil; air filters; tires rotated; etc). Ranger was built in February, 2020.

I notice I do lose some coolant from time to time, but I never have to refill the reservoir more than 1/2." Remember, I do live in the desert heat.

What could be wrong?

Do you think I can drive the vehicle?

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[JesseS]

P0471 is a diagnostic trouble code (DTC) for "Exhaust Pressure Sensor Range/Performance". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause. I would say it needs to go in if it will not reset.

 

[diesel924]

That code sets if the sensor sees that the signal to the PCM is out of the calibrated value range. You could try replacing the sensor but it really needs a mechanic to check it. The PCM is looking for a signal that is over the BARO sensor reading by some amount while the engine is running.

 

[airline tech]

That code is for the EGR Pressure sensor, you may have a bed sensor but with you stating loss of coolant, possibly means that the EGR Cooler is leaking into the exhaust system.
So, you do not see any leaking coolant on the ground.

Note: This is not the DPFE Sensor that has plagued the Ranger, this is another sensor in the system.

This is the Primary Function of the Sensor, and with you having loss of coolant, might be a leaking EGR Cooler, causing the code.

The EP sensor (if equipped) measures the exhaust pressure by comparing the EP sensor calibrated value to the actual EP sensor value. The EP sensor is used primarily to determine EGR cooler effectiveness and is also used for converting EGR flow to EGR valve position.


There was another post on this preciously.

 

[airline tech]

FYI: Ref code not clearing but light went out
The code will stay until the automatic drive cycle test has completed, if it passes the light will stay off, if it fails the light will come back on.
Might just be a onetime glitch for the code, but the occasional loss of coolant might be something to watch closely.

 

[Superdannyboy]

Here's my coolant level. Built 9/19. Never added coolant.

 

[ctechbob]

Here's my coolant level. Built 9/19. Never added coolant.

If you've never added coolant you don't have a problem. Pretty much any car will see a tiny bit of coolant loss over the years, and if yours has only dropped that much in 4 years you're fine.

 

[Desert Sage]

After a 3 day stint at the dealer, my Ranger is home. It turns out the Exhaust Back Pressure Sensor was faulty. I did not realize EGR systems were installed on GAS engines, for it's more common on diesel engines- like with our cousin Rangers in Australia. In any event, the EBPS sensor was replaced, the connecting tube was flushed out and cleaned, all under Ford's Extended Power Warranty at no charge. Once I go over 60,000 miles, if the sensor fails again, it will be covered under the Ford Extended Warranty. Thanks to all of you that helped on this thread- I'm enclosing the paperwork from the dealer in case anybody else gets the dreaded P0471 code. Thanks again everybody!!

 

[P. A. Schilke]

After a 3 day stint at the dealer, my Ranger is home. It turns out the Exhaust Back Pressure Sensor was faulty. I did not realize EGR systems were installed on GAS engines, for it's more common on diesel engines- like with our cousin Rangers in Australia. In any event, the EBPS sensor was replaced, the connecting tube was flushed out and cleaned, all under Ford's Extended Power Warranty at no charge. Once I go over 60,000 miles, if the sensor fails again, it will be covered under the Ford Extended Warranty. Thanks to all of you that helped on this thread- I'm enclosing the paperwork from the dealer in case anybody else gets the dreaded P0471 code. Thanks again everybody!!

Hi Lowell,

Gas engines have had EGR since the mid 1970s....

Best,
Phil

 

[Desert Sage]

Thanks Phil- once diagnosed by the dealer, I tried to research information on the politics of the EGR, and it seemed most of the articles dealt with EGR's with diesel engines. And thanks, I had no idea that EGR's with gas engines went all the way back to the 1970's. Would there have been any way for me to diagnose the faulty sensor without going to the dealer? The dealer did good work, but I had to wait days to get it in, and not knowing what was specifically wrong, and being old school- when that engine light went on, that meant inevitable catastrophic engine failure- so I stopped using the truck right away.

 

[airline tech]

Using the code they used pinpoint tests in the manuals and viewed live data on the scan tool. Sometimes though the code given for some systems such as EGR and EVAP can be misleading and most will just throw a part at it, only to find it did not fix the issue.
I suggest find some videos for Scanner Danner- this guy is by far the very best on YouTube for explaining Scanner diagnostic troubleshooting. I posted one of his videos on here somewhere on a 97 Ranger, although older it gives a base understanding of what is involved in troubleshooting a EGR system

 

[P. A. Schilke]

Thanks Phil- once diagnosed by the dealer, I tried to research information on the politics of the EGR, and it seemed most of the articles dealt with EGR's with diesel engines. And thanks, I had no idea that EGR's with gas engines went all the way back to the 1970's. Would there have been any way for me to diagnose the faulty sensor without going to the dealer? The dealer did good work, but I had to wait days to get it in, and not knowing what was specifically wrong, and being old school- when that engine light went on, that meant inevitable catastrophic engine failure- so I stopped using the truck right away.

Hi Al,

The first EGR systems were engine vacuum operated via a PVS (Ported Vacuum Switch). Diagnostics back then were quite simple. Pull the vacuum line and see if it made in engine operation...if not remove and clean the EGR Valve. Then with EEC VI we had EGR Valve Position Sensors to tell how much opening the EGR Valve had and a variable amount of EGR which improved driveability over the old vacuum on or off systems. This introduce the VIP diagnostics system with a code system of light blinks or audible beeps to assist in diagnostics. Two digit codes with a pause between codes. 1-1 was a system pass for example. Now where we are today is so much more complex with modules interacting etc...UG...

best,
Phil

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