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Greg, Technician
Category: Dodge
Satisfied Customers: 7057
Experience:  17 years Shop Owner /Technician. 27 years experience,
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My 2007 dodge ram 1500 truck, 4.7L flex fuel will show

Customer Question

my 2007 dodge ram 1500 truck, 4.7L flex fuel will show engine codes, 171, 172, 175 (plus less frequent 174) and when cleared, most often shows 171 and 175. Since they are so intermittent, I am hesitant to just start changing O2 sensors. They come on after the engine runs for a period of time (say 5 mins). I believe that ther may be no Mass Airflow sensor or easy serviceable fuel filter
Submitted: 1 year ago.
Category: Dodge
Expert:  Greg replied 1 year ago.

Did you change the air flow meter .??

Did you check the fuel pressure ??

Having all these codes .

What are the short trim readings at idle and at 2500 rpm .

See this quite often and its normally the Airflow meter .which does not have to tyrip a AFM code as it

may be working with in its set parameters.

What are the AFM reading at idle .

Rgds Greg

Customer: replied 1 year ago.
1. Have not changed anything, as yet.
2. I am not familiar with the Airflow meter part, or where it's located.
3. Would need to acquire a fuel pressure gauge.
4. Do not know what short trim readings @ 2500 rpms means.
5. Do not know what an AFM is.Bill
Expert:  Greg replied 1 year ago.

Okay this is a dodgy issue as if not diagnosed correctly you could end up throwing parts at this car and still not repair .

I would suggest you find a shop that can do the diagnostics for you , this they would call for an hrs diagnostic time and

would be money well spent .

Or if you have the possibility to try parts from a known working dodge like yours i would first try the MAP .not the MAF sorry misprint .

As the MAP is the biggest culprit for these codes .

This is located right on front of the manifold just behind the alternator .

Will take a photo of one in the morning as have one in the shop at the moment.

Rgds Greg

Customer: replied 1 year ago.
Thanks, ***** ***** same about changing a lot of parts. Will pick up a map sensor and a fuel pressure test gauge tomorrow (someone must have borrowed mine ??)
Expert:  Greg replied 1 year ago.

Do you have the use of a good scan tool with live data ,


Customer: replied 1 year ago.
Not readily, just have a basic code reader.
Expert:  Greg replied 1 year ago.

Don't want you to spend money on a MAP with out first testing it .

Do you have a hard starting when cold .

Black smoke out the exhaust .

Rough idle little lack of power.


Expert:  Greg replied 1 year ago.

First start with fuel pressure test as you have codes for lean and rich running engine .

And if you can have a scan tool set up in live data and check the fuel trim this will tell us a lot ..


Customer: replied 1 year ago.
it doesn't start easily in the morning, like it use to. It does have a lot of black smoke at first and does not idle well, all the time. Kind of goes through a period of bad - good - bad again, and then will throw a code if previously cleared.
Expert:  Greg replied 1 year ago.

Okay this does sound like the MAP sensor , if no tool to test go ahead and replace the sensor .

Then get back to me if needed .

Kindest regards Greg

Customer: replied 1 year ago.
Sorry, never had a chance to get back to you, due to work out of town. After changing the MAP sensor and a O2 bank 1 sensor, most of the codes cleared (P0175 remained) and the truck was running very good. The very next morning, it would turn over but never start. It has good fuel pressure at 54 psi, all fuses are good. It would not try to start with a little gas misted into intake. Have disconnected the battery to try to re-set, whatever. Hope its not the TIPM !! Forgot to mention previously, but a few weeks ago the EGR Valve had been changed. Codes from before were: 171,172, 174, 175.
Expert:  Greg replied 1 year ago.

Okay so after replacing the MAP sensor car started to run better .

But now after a days the engine will now not start .

The codes 171,172, 174, 175.are what you now have after clearing all codes after fitting the MAP sensor.

These are all lean and rich codes . also pointing to the MAP sensor , try your old one ans see if she starts .


Customer: replied 1 year ago.
Put orig map back in with same result. Still no start, fuel sys seems good. There may be a very slight attempt to start, but very very short.
Expert:  Greg replied 1 year ago.

Any other codes besides the ones you gave me .

Try starting with your foot flat out on the accelerator could be flooding .


Customer: replied 1 year ago.
No other codes, than the 175 (which had been cleared by code reader). Have tried the gas pedal thing, since day one. I am curious if there may be an ignition switch issue because, it is pretty loose and actually hangs up sometimes in the "starter engage" position. (sorry, forgot to say that earlier). Was trying to figure out how the switch works, i.e., assuming it sends 12V somewhere, what is the wire location or color to TIPM or PCM or another place first. Did see something about a pink/white wire leaving the switch.
We think that we get a very slight/short ignition attempt, randomly. It's so quick, that it makes you wonder if that was an ignition attempt or not. So, will try to look up the wiring out of the switch. I assume that it controls something other the starter, which always turns over. Took all the connectors off of the TIPM, cleaned and reseated, tried new crankshaft sensor and camshaft sensors. Figured, for their price, it was still cheaper than a tow to a shop with the proper scan tool. I am quite a distance away from a dealer or shop with such a tool. Lots of small repair shops around, although.
Expert:  Greg replied 1 year ago.

Check a local repair shop they will have the tools for this .they have to.

with out they can not work .

A shop today that has no scan tool is like a car with out its keys .ring a local indy shop and ask .

Rgds Greg