DTC Codes P1401, P1120, P1121, P0122 and more

[429CJ-3X2]

No CEL, but I scanned for codes and got the following

KOEO
P1401 Differential Pressure Feedback EGR Circuit High Input
P1120 Throttle Position Sensor A out of range low (Ratch too low)
P0122 Throttle/pedal Sensor A circuit low input
P1121 Throttle Position Sensor A inconsistent with MAF/MAP Sensor

KOER,
P1401
P1120
P1780 Transmission Control Switch (O/D Cancel) Circuit out of self test range
P0505 IAC System
P1464 A/C Demand out of self test range (I didn't think to turn off the a/c before running the test)

All I've done to the truck recently is change the fuel pump and filter a month ago, and a new air filter and cleaned the MAF 2 months ago. Did have a Check Fuel Cap light before changing the fuel pump, but it hasn't come back (500 miles).

What do I need to do? How serious are these codes? Taking a 1400 mile round trip next week.

 

[429CJ-3X2]

I started this thread Friday knowing I wouldn't have time until evening, at best, to research the codes and fixes, and would have somewhat limited time to do the repairs before leaving for Ohio tomorrow in the ST. After researching, I replaced the TPS, DPFE sensor, and cleaned the IAC and throttle body. These are all easy to do and require only a couple of basic tools.
After doing the above and erasing the codes, the truck ran better, but the idle, both in Park and Drive was considerably higher than it should have been. The only code still showing was P0122 Throttle/Pedal Position Sensor A Circuit low input. More research turned up this procedure to reset the TPS.

https://knowhow.napaonline.com/how-to-reset-a-throttle-position-sensor/

Went for a test drive this evening after doing the reset procedure. Idles like it should, and runs stronger than it has in some time. It's been shifting weird, which largely but not entirely cleared up after the new fuel pump last month. The above codes can cause shifting issues, as well as poor mileage. All shifts now seem very smooth as they should. Mileage lately has sucked. Last few tankfuls have netted 13-15 mpg. That's dead of the winter mpg. Should be getting 16+ in normal local driving this time of year. The trip to Ohio in May averaged just under 17 mpg. Got almost 20 on the same trip in the winter. That trip was exceptional. It normally averages a bit less. Buy gas at mostly the same stations going both directions. We're leaving for Columbus again tomorrow afternoon (1400 miles round trip). Hoping to average 19-20 mpg again!

When I get back home, I need to pull the instrument cluster and replace some bulbs, including the CEL which is almost certainly burned out. Most of the above codes don't cause the CEL to light up, but the P1401 should have.

 

[amj441]

P1401 Check the differential pressure sensor readings in scan tool. the wiring may be disconnected and showing a high signal, or the sensor may be clogged up.

p1120 seems like your throttle position sensor may be out of range? check with a scanner and few live data for smooth consistent lines. make sure that it can read slight throttle inputs.

p0505? are you experiencing any erratic idles? high idle? surging? very generic code for several issues.

 

[410Fortune]

It sounds like he has resolved the issues
Throttle position sensor being the main culprit and it was fixed with a new part and a reset

Very interesting as I have a sohc auto truck with some funky shifting and a throttle position sensor out of range code just re appeared

Thanks for the thread and info!

Did the tps reset procedure actually work on the sport trax? How would you tell with a burnout cel?
That reset procedure is listed as being for drive by wire trucks

I have always tested tps
With a multimeter and a sweep test
Never attempted to “reset” one

 

[429CJ-3X2]

The reset did work. Idle was way too high before the reset procedure, and is perfect now. I also scanned for codes after driving a few miles.
Last trip to Ohio, rpms at 72-73 mph were around either 2250 or so, or 2800. It was like it was somewhere between OD on and OD off. Don't know how that's possible, but one of the codes indicated confusion in the OD on/off system. This trip, rpms have been steady at the lower number where it should be.

Gas mileage is back! I just filled up for the return trip, and so far we're averaging 20.1 mpg. Can't ask for much better than that the way the truck is loaded. There was a breeze from the south on the way here, traveling ESE, but it wasn't noticeable. Might have helped a tiny bit.

 

[429CJ-3X2]

The reset procedure might not be necessary. Some say the computer eventually relearns the proper positioning, but I didn't have time to wait and see before our road trip.

All shifts were smooth and on time.

To correct what I said above, 65 mph = approx 2250 rpm. 73 mph = about 2800 rpm.

We got 20.1 mpg on the way to Columbus, including about 50 miles in Columbus (still mostly interstate), and 19.6 mpg on the way home. Wind wasn't a big factor either direction. Temperature was right at 90 degrees Wed, Thurs, and Fri, with humidity to match. Today was upper 70s to low 80s with rain showers at times. Gas was mostly 15% ethanol, with the remainder being 10% ethanol. (This is the Corn Belt!)

 

[410Fortune]

That’s dang good mileage for one of these suckers loaded up and trippin
I often wish we had a 6th gear so at 78 mph we were at 1800 rpm
My sport trac w 5.0 and 4.1 on 265 tires is like you 2800 rpm at 75-80
I need bigger tires or a 6th gear lol

 

[429CJ-3X2]

That is very good gas mileage, but 5 days later, I'm still bugged that it got "only" 19.6 mpg on the way back after getting 20.1 on the way there. It's only .5 mpg, but it bugs me! Maybe it was the rain, but the humidity was 80-90% on the way out, it just wasn't falling out of the sky!