My 1994 El Dorado is giving diagnostic codes PO38 (open IAT sensor)and PO71 (intermittent MAP). Not sure what these mean and/or if these are critical issues that need immediate attention. Please advise

AWH: Cadillac On-Board Diagnostic Trouble Codes (OBD)

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Diagnostic Trouble Codes for OBD I equipped General Motors (GMC, ... BCM Codes; ECM Codes; PCM Codes; IPC Codes; ABS Codes; SIR Codes ..... LR Wheel Speed Sensor Frequency Error T037 . ...... Intermittent TPS Signal P071 (E071) . ..... NOTE: The part numbers listed above are for the Cadillac Deville, Eldorado ...

Lightbulb Re: How can I check for any codes Im throwing ...

www.cadillacforums.com > ... > Past Cadillac Vehicle Discussion

Jan 28, 2004 - 11 posts - ‎8 authors
I heard that if you hold temp and off, it will show you the codes you are throwing. ...Cadillac DeVille 1985 to 2005 including: ... Diagnostic Trouble Codes for OBD I equipped General Motors (GMC, Chevrolet, Buick, Oldsmobile, .... T037 .......... .............................. LR Wheel Speed Sensor Continuity Fault T041 .

Trouble Code Help???? OBD1 Codes, 1993 GM Cadillac El Dorado ...

www.cadillacforum.com > ... > General Technical Section > General Tech

Nov 30, 2007 - I retrieved these codes : PO31, PO52, PO53, PO91, IO39, IO52, AO48 they had History behind them but Iwant to know what these mean and are ...

P0303 Code - Cylinder #3 Misfire
P0110 DTC - IAT Circuit Malfunction
P2195 O2 Sensor Signal Biased/Stuck Lean (Bank 1 Sensor 1) Code
Potential causes of a P2195 code include:
p2195
p219521

• Oxygen (O2) or A/F ratio sensor or sensor heater malfunction
• Open or short in O2 sensor circuit (wiring, harness)
• Fuel pressure or fuel injector problem
• Faulty PCM
• Intake air or engine vacuum leaks
• Faulty fuel injector(s)
• Fuel pressure too high or too low
• PCV system leak/fault
• A/F sensor relay faulty
• MAF sensor malfunction
• ECT sensor malfunction
• Fuel pressure too low
• Fuel leak
• Air suction in air intake system
• A code P0303 may mean that one or more of the following has happened:
  

• Faulty spark plug or wire
• Faulty coil (pack)
• Faulty oxygen sensor(s)
• Faulty fuel injector
• Burned exhaust valve
• Faulty catalytic converter(s)
• Running out of fuel
• Poor compression
• Defective computer
• Potential causes of the P0110 DTC include:
  
• 
  po110
  • IAT sensor shifted out of airflow
  • Bad IAT sensor
  • Shorted to ground or open on signal circuit to IAT
  • Open in ground circuit to IAT
  • Poor connection at IAT (backed out terminals, broken connector locks, etc.)
  • Bad PCM

The IAT (Intake Air Temperature) sensor is a thermistor that varies resistance based upon the temperature of the engine intake air. Usually a two wire sensor. One wire is supplied 5 Volt from the PCM (Powertrain Control Module) and the other is a ground. The PCM monitors the change in the 5 Volt supplied to determine air temperature. When the intake air is cold, the resistance is high, resulting in a high signal voltage.


When the intake air is warm, the reistance is low, resulting in a low signal voltage. This code means that the PCM saw a larger-than-normal change in a shorter-than-expected time on the IAT signal circuit.




Since this code is likely pointing to an intermittent problem on the IAT circuit, there may not be any symptoms at present. However, the MIL will likely be on. The car MAY exhibit some drivability problems, but it is more likely that there will be no noticeable symptoms to the driver.




Potential causes of the P0111 DTC include:
a bad IAT sensor
an open in the signal or ground circuit
a short to ground on the signal circuit
poor connection at sensor or PCM




Possible Solutions:
If there are other IAT codes present, diagnose them first. If not, then, using a scan tool verify the IAT voltage with KOEO (Key on engine off).


If, on a cold engine it reads the same as the CTS (Coolant temperature sensor), then the problem is intermittent. But if the IAT reading isn't the same as the CTS refer to diagnostic procedure for P0110. If your scan tool has a freeze frame failure records feature, use it to see what the IAT reading was at the time of the failure. If the reading was at negative 30 or so degrees F (indicating it was at the extreme coldest reading), then there was an intermittent high resistance reading on the IAT signal circuit.


Check for an open ground on the ground circuit and signal circuit. If they are OK, try raising and lowering the temperature of the IAT sensor artificially. Do this by removing the IAT and putting it in a freezer and then applying heat with a heat gun (be careful not to apply too much heat to the IAT with the heat gun or it'll melt the sensor). Watch the resistance change using an ohmmeter attached to each terminal. It should vary smoothly with no sudden jumps. If the reading jumps suddenly, then repace the IAT sensor.


However if the freeze frame reading was at the highest extreme (above 250 deg. F) then there was an intermittent low resistance on the signal circuit. Check for a short to ground on the signal circuit. If it appears OK, then do the above artificial heat test and replace the IAT as necessary. If the problem can't be duplicated, use a voltmeter to watch the signal voltage as you "wiggle" test the wiring harness. Watch for a sudden change in voltage indicating a short or open. Replace IAT as necessary.


This is a pretty simple code and it only really looks for extremely short changes that are relatively high in voltage. It's usually the sensor that is bad unless the vehicle is extremely old, in which case there may be harness problems.




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P0106 - MAP/Barometric Pressure Circuit Range/Performance ProblemOBD-II Trouble Code Technical Description

Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem

What does that mean? The Powertrain Control Module (PCM) uses the Manifold Absolute Pressure Sensor (MAP) to monitor engine load. (NOTE: Some vehicles have a Barometric Pressure (BARO) sensor that is integral to the Mass Air Flow (MAF) sensor and do not have a MAP sensor. Other vehicles have a MAF/BARO and a redundant MAP sensor where the MAP sensor functions as a backup input in case of MAF failure.) The PCM supplies a 5 Volt reference signal to the MAP sensor. Usually the PCM also supplies a ground circuit to the MAP sensor as well. As the manifold pressure changes with load, the MAP sensor input informs the PCM. At idle the voltage should be 1 to 1.5 Volts and approximately 4.5 Volts at Wide Open Throttle (WOT). The PCM looks for any change in manifold pressure to be preceded by a change in engine load in the form of changes in throttle angle, engine speed, or Exhaust Gas Recirculation (EGR) flow. If the PCM doesn't see any of these factors change while detecting a rapid change in MAP value, it will set a P0106.
Causes A P0106 could be caused by:

• Bad MAP sensor
• Water/dirt intrusion affecting MAP sensor connector
• Intermittent open in the reference, ground, or signal wire for the MAP sensor
• Intermittent short in the reference, ground, or signal wire for the MAP sensor
• Ground problem due to corrosion causing intermittent signal problem
• A break in the flexible air intake duct between the MAF and the intake manifold
• Bad PCM (do not assume the PCM is bad until you've exhausted all other possibilities)

Possible Solutions Using a scan tool, watch the MAP sensor value with the key on, engine off. Compare the BARO reading with the MAP reading. They should be roughly equal. The voltage for the MAP sensor should read approx. 4.5 volts. Now start the engine and look for a significant drop in the MAP sensor voltage indicating the MAP sensor is working.
If the MAP reading doesn't change perform the following:

1. With the Key on, engine off, disconnect the vacuum hose from the MAP sensor. Using a vacuum pump, pull 20 in. of vacuum on the MAP sensor. Does the voltage drop? It should. If it doesn't inspect the MAP sensor vacuum port and vacuum hose to manifold for a restriction of some kind. Repair or replace as necessary.
2. If there are no restrictions, and the value doesn't change with vacuum, then perform the following: with the Key on and engine off and the MAP sensor unplugged, check for 5 Volts at the reference wire to the MAP sensor connector with a Digital Voltmeter. If there is none, check for reference voltage at the PCM connector. If the reference voltage is present at the PCM connector but not the MAP connector, check for open or short in the reference wire between MAP and PCM and retest.
3. If reference voltage is present, then check for existing ground at the MAP sensor connector. If it isn't present then repair open/short in the ground circuit.
4. If ground is present, then replace MAP sensor.

Other MAP sensor trouble codes include P0105, P0107, P0108 and P0109.
P0128 OBD-II Trouble Code Technical Description

Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
What does that mean? This means that the engine's PCM detected that the engine has not reached the required temperature level within a specified amount of time after starting the engine. The intent of the P0128 code is to indicate a faulty thermostat. Similar codes: P0125
In determining the engine did not reach a "normal" temperature, it takes into account the length of time the vehicle has been running, the intake air temperature (IAT) sensor reading, the engine coolant temperature (ECT) sensor reading, and the speed of the vehicle.

Causes A code P0128 may mean that one or more of the following has happened:

• Low engine coolant level
• Leaking or stuck open thermostat
• Faulty cooling fan (running too much)
• Faulty coolant temperature (ECT) sensor
• Faulty intake air temperature (IAT) sensor

Possible Solutions Past experience indicates that the most likely solution is to replace the thermostat. However here are some suggestions on troubleshooting and repairing a P0128 OBD-II code:

• Verify coolant strength & level
• Verify proper cooling fan operation (check if it's running more than it should). Replace if necessary.
• Verify proper engine coolant temperature (ECT) sensor operation, replace if necessary.
• Verify proper intake air temperature (IAT) sensor operation, replace if necessary.
• If the above items check out good, replace the thermostat

You are a OBD 1 just disconnect the battery, but because you are a cadillac it will just detect the problem it will look for shorts open and ground so you have a problem do a code reading on you vehicle you will jump wire connection at the diagnostic area and read the blinking light, there just fix the problem plus with the cost of fuel it pays to repair itself

have the shift lock interlock solenoid checked out

CODE PO172 - FUEL SYSTEM RICH BANK 1 CONDITIONS. POSSIBLE CAUSES : 1. BASE ENGINE MECHANICAL FAULT AFFECTING ONE OR MORE CYLINDERS. 2.EVAP SYSTEM COMPONENT HAS FAILED OR CANISTER FUEL SATURATED. 3.FUEL CONTROL SENSOR IS OUT OF CALIBRATION.( ECT IAT MAP ) 4. FUEL SYSTEM SUPPLYING TOO MUCH FUEL AT IDLE SPEED OR AT CRUISE. 5. FUEL INJECTOR(S) IS LEAKING OR STUCK PARTIALLY OPEN. ( ONE OR MORE ) 6. HO2S IS CONTAMINATED DETERIORATED OR IT HAS FAILED.

Try unplugging and plugging the map sensor, this device should have manifold pressure hooked up to it, via hose, so check for cracks or leaks. Then clear codes and test again.

P0110 - Intake Air Temperature (IAT) Sensor Circuit

P0111 - Intake Air Temperature (IAT) Sensor Performance

P0112 - Intake Air Temperature (IAT) Sensor Circuit Low Voltage

P0113 - Intake Air Temperature (IAT) Sensor Circuit High Voltage

P0114 - Intake Air Temperature Circuit Intermittent ,hope this helps you