How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Dan Your Own Question
Dan
Dan, ASE Certified Technician
Category: Subaru
Satisfied Customers: 1655
Experience:  Auto Technician
94707146
Type Your Subaru Question Here...
Dan is online now
A new question is answered every 9 seconds

P0172 code reading, flashing cruise control and brake

Customer Question

P0172 code reading, flashing cruise control and brake lights, low idle, occasionally near stalling
JA: While using the cruise control can you accelerate or decelerate? Have you checked the fuses?
Customer: HAven't tried to use the C/C, only noticed its blinking
JA: What is the model/year of your Subaru?
Customer: 2010 Outback
JA: Are you fixing your Outback yourself? What have you tried so far?
Customer: I'm overseas unfortunately so a lot of it is up to me. there's no dealer. just pulled the code myself
JA: Anything else you want the mechanic to know before I connect you?
Customer: Does this cost anything?
Submitted: 9 months ago.
Category: Subaru
Expert:  Dan replied 9 months ago.

Hello my name is***** am an ASE Master Technician and I am glad to help you out with your question.

Expert:  Dan replied 9 months ago.

p0172

TROUBLE SYMPTOM

  • Improper idling
  • Engine stalls.
  • Poor driving performance

CAUTION: After servicing or replacing faulty parts, perform Clear Memory Mode Ref. to OPERATION , Clear Memory Mode, and Inspection Mode Ref. to PROCEDURE , Inspection Mode.

DIAGNOSTIC PROCEDURE

StepCheckYesNo

1 CHECK EXHAUST SYSTEM. Are there holes or loose bolts on exhaust system?Repair the exhaust system.Go to step 2 .

2 CHECK AIR INTAKE SYSTEM. Are there holes, loose bolts or disconnection of hose on air intake system?Repair the air intake system.Go to step 3 .

3 CHECK FUEL PRESSURE.

WARNING: Place "NO OPEN FLAMES" signs near the working area.

CAUTION: Be careful not to spill fuel.

Measure the fuel pressure. Ref. to INSPECTION , Fuel Pressure.

CAUTION: Release fuel pressure before removing the fuel pressure gauge.

Is the measured value 339.5 - 360.5 kPa (3.5 - 3.7 kg/cm2 , 49 - 52 psi)?Go to step 4 .Repair the following item.
Fuel pressure is too high:

  • Clogged fuel line or bent hose

    Fuel pressure is too low:

  • Improper fuel pump discharge
  • Clogged fuel line

4 CHECK ENGINE COOLANT TEMPERATURE SENSOR.

  1. Start the engine and warm up completely.
  2. Read the data of engine coolant temperature sensor signal using Subaru Select Monitor or general scan tool.NOTE:
    • Subaru Select Monitor

      For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". Ref. to SUBARU SELECT MONITOR .

    • General scan tool

      For detailed operation procedures, refer to the general scan tool operation manual.

Is the temperature 75°C (167°F) or more?Go to step 5 .Replace the engine coolant temperature sensor. Ref. to ENGINE COOLANT TEMPERATURE SENSOR .5 CHECK MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR.

  1. Start the engine and warm up engine until coolant temperature is higher than 75°C (167°F).
  2. For CVT models, set the select lever to "P" range or "N" range, and for MT models, place the shift lever in the neutral position.
  3. Turn the A/C switch to OFF.
  4. Turn all the accessory switches to OFF.
  5. Read the data of mass air flow and intake air temperature sensor signal using Subaru Select Monitor or general scan tool.NOTE:
    • Subaru Select Monitor

      For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". Ref. to SUBARU SELECT MONITOR .

    • General scan tool

      For detailed operation procedures, refer to the general scan tool operation manual.

Is the measured value 2.0 - 5.0 g/s (0.26 - 0.66 lb/m)?Go to step 6 .Replace the mass air flow and intake air temperature sensor. Ref. to MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR .6 CHECK MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR.

  1. Start the engine and warm up engine until coolant temperature is higher than 70°C (158°F).
  2. For CVT models, set the select lever to "P" range or "N" range, and for MT models, place the shift lever in the neutral position.
  3. Turn the A/C switch to OFF.
  4. Turn all the accessory switches to OFF.
  5. Open the front hood.
  6. Measure the ambient temperature.
  7. Read the data of mass air flow and intake air temperature sensor signal using Subaru Select Monitor or general scan tool.NOTE:
    • Subaru Select Monitor

      For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". Ref. to SUBARU SELECT MONITOR .

    • General scan tool

      For detailed operation procedures, refer to the general scan tool operation manual.

Subtract ambient temperature from intake air temperature. Is the obtained value -10-50°C (-18 -90°F)?Repair the poor contact of ECM connector.Check the mass air flow and intake air temperature sensor. Ref. to MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR .

Expert:  Dan replied 9 months ago.

Please reply to this if you need more help and we can continue this conversation. If you are satisfied with my service, please rate at the top of the screen. Rating does not close out your question. Remember, sometimes it is difficult to completely diagnose your vehicle without being there, but I will try to give you the best answer I can. If I am not giving you 5 star service, please let me know what I missed.

Thanks,

Dan

Expert:  Dan replied 9 months ago.

Hello again Dan here,

I am contacting you because the post has not been closed or rated.

This question is coming up on 7 days which means it will time out and close.

You have already paid to get this question answered, but you have not rated.

Let me help some more. Is there anything else I can help you with?

If I did not give you 5 star service, please let me know what I missed.

I do not get compensated for my time and resources unless you rate me.

Thanks

Related Subaru Questions