2004 Ram 2500 5.9L H.O. Cummins keeps turning on CEL and throwing code P0299 turbocharger underboost. Replaced 1 bad MAP/IAT sensor already. Lasted about 585 miles code is back on.

question edited for clarity

The P0299 error code reveals that your vehicle's supercharger or turbocharger is not working correctly. ... The error commonly appears when the ECU detects low turbocharger or supercharger low boost pressure. This parameter is continuously monitored by ECU, which uses the boost pressure sensor or/and the MAP sensor.

May 22, 2019

What Does Error Code PO299 Mean? - Taylor Diesel Group

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the following answer is courtsey of OBD-CODES.com OBD Codes Your OBD-II Trouble Codes Repair Site Home Trouble Codes FAQs Forums Store P0299 Turbo / Supercharger Underboost OBD-II Trouble Code Technical Description Turbocharger/Supercharger "A" Underboost Condition What does that mean? The P0299 DTC code refers to a condition where the PCM/ECM (powertrain/engine control module) has detected that the bank "A" or single turbocharger or supercharger is not providing a normal amount of boost. That could be due to a variety of reasons, which we detail below. On a normally operating turbocharged or supercharged engine the air going into the engine is pressurized and that's part of what makes so much power for an engine of it's size. If this code is set, you will likely notice reduced power output. In the case of Ford vehicles, this may apply: "The PCM checks for a minimum throttle intake pressure (TIP) PID reading during engine operation, which indicates an underboost condition. This DTC sets when the PCM detects that the actual throttle intake pressure is less than the desired throttle intake pressure by 4 psi or more for 5 seconds." Symptoms Symptoms of a P0299 DTC may include: MIL (Malfunction indicator lamp) illumination Reduced power output from engine, possibly in a limp mode Unusual sounds from the engine/turbo There would likely be no other symptoms. Potential Causes Potential causes of a P0299 turbo underboost code include: Intake (induction) air restriction or leak Failed or damaged turbocharger (sticking, binding, etc.) Faulty boost/charge pressure sensor Faulty wastegate bypass regulator valve (VW) Low fuel pressure condition (Isuzu) Sticking turbo nozzle control solenoid (Isuzu) Faulty injector control pressure (ICP) sensor (Ford) Low oil pressure (Ford) EGR system fault (Ford) Variable geometry turbocharger (VGT) actuator (Ford) VGT vanes sticking (Ford) Possible Solutions First off, you'll want to repair any other DTC codes if present prior to diagnosing this code. Start with a visual inspection. Inspect the intake air system for cracks, loose or disconnected hoses, restrictions, blockages, etc. Repair or replace as required. If the air induction system tests OK, then you'll want to focus your diagnosis efforts on the charge pressure control, diverter valve (blowoff valve), sensors, regulators, etc. Really at this point you'll want to refer to a vehicle specific detailed repair manual for specific troubleshooting steps. There are some known issues on certain makes and engines so also check out our car repair forums here and search using your keywords. For example, if you search around, you'll find that a common fix for a P0299 in VWs is to replace or repair the diverter valve or wastegate solenoid. On the GM Duramax diesel, this code may mean the turbo housing resonator has failed. If you have a Ford, you'll want to next check the wastegate regulating valve solenoid for correct operation

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P0299 Volkswagen Turbocharger Engine Underboost

Notice that 2 of the 3 causes are related to the turbo. A waste gate is the dump valve to let the air out when the engine is not consuming all the air that the turbo is creating.

will cause limphome ,low power, and mpg bad, and CEL glow.
IAT is major sensor on MAP EFI.

the IAT reads too high, id bet it's unplugged.
or was removed and dropped to the pavement and broken inside.
the eCU reports this when the input hits near 5vdc.
this is and open circuit stated.
fell off, wires bad. connector bad. dead open sensor bad.
my fsm has no IAT resistance table. (sad)

my garage is 60f and my sensor reads 16k ohms (16,000)
with hot water (tap at sink) running over it , it might read
3000 ohms, or 3k. it is a NTC sensor, more heat , lower ohms.

the sensor is double locked, so never fall off.
slide red lock up, and mush lever down and pull conn. off sensor.
3 steps.



THE fsm STATES
K21) IAT SIGNAL CIRCUIT SHORTED TO VOLTAGE (12V?)
(K21) IAT SIGNAL CIRCUIT OPEN (FELL OFF?)
(K900) SENSOR GROUND CIRCUIT OPEN (FELL OFF)
IAT SENSOR (BAD)
POWERTRAIN CONTROL MODULE (PCM) nah.

P0299 VOLKSWAGEN - Turbocharger Engine Underboost
Possible causes- Faulty Wastegate Bypass Regulator Valve
- Mechanical damage at Turbo/Super Charger
- Faulty Charge Air Pressure Sensor

It's a map/tps sensor correlation code, essentially it means the map sensor reading isn't what's expected with the tps reading and vice versa! It sounds like your tps sensor is probably bad or the circuit to one of those 2 sensors.

Hope helps (remember rated this).

0191 is fuel rail pressure sensor circuit range/performance 0193 fuel rail sensor circuit high input 0652 sensor reference voltage b circuit low 0341 cam shaft position sensor a circuit range/performance (bank1 or single sensor) and 0069 map barometric pressure correlation
i hope that helps you some what

P0243 Turbocharger Wastegate Solenoid 1

You can find them all here:

http://www.allpar.com/fix/computer-codes.html

code#2146 fuel injector group a supply voltage ckt (open) code# po299 turbo/supercharger (underboost) code# po483 control fan rationality check (malfunction) code# po513 immobilizer (incorrect)

check with vw theres a technical service bulletin issued in dec o7 number 0107-70 its for code P0299 on 2006--- 2.0L turbo vw engines