Skip the auto shop - Our mechanics make house calls

Q: Check engine light on.

asked by on

I have a 95 I6 4.9L with a check egine light on (turns on and off speratically). I had a guy scan with a computer and got a P0171, and another evp ept voltage low. I bought and changed the O2 sensor, as well as the canister purge valve (w/new hoses), per advice. I then figured out how to run the on board EEC-IV using the CIL and got codes: 327 Electronic pressure transducer (EPT)/differential pressure feedback exhaust (DPFE) sensor/electronic vacuum regulator (EVR) 522 Neutral/drive switch (NDS) 512 Keep alive memory (KAM) fault 111 All systems OK Replaced both battery terminal ends and a new battery. I've checked EGR Vacuum Solenoid for carbon buildup, but was clean. Intake manifold, throttle body gasket replaced. I have checked all other hoses for a vac leak using a can of starting fluid but all seems fine. Not to sure where to go from here. Thanks in advance for your help

My car has 268000 miles.
My car has a manual transmission.

The testing you did using the CIL may not have been done correctly. During these tests you will need to cycle the clutch and accelerate the engine when the separator codes were received. This is done with a superstar 2 or NGS tester or equal. The test without a proper tester may not work correctly. The code 327 may be a good code but the others may not. I suggest having the DPFE checked using pinpoint tests with a vacuum pump to see if the EGR valve sticks when opening. If the valve sticks, and then pops open can cause the code. I recommend having a certified technician scan the computer for codes and inspect the vehicle in person in order to have this accurately diagnosed and repaired.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Front passenger side 1995 Volkswagon Eurovan T4

Hello - your Eurovan utilizes a torsion bar to support the weight of the front end of your vehicle. Torsion bars can weaken with age, use, and driving conditions. This results in "sinking" or lowering of the body. You may...

Q: Check engine light on, engine knocking, loss of power, and coolant leaking.

Hi there. Grab a flashlight and look under the vehicle for where the coolant leak is coming from. Either there is a gasket, hose, or freeze plug that is leaking causing the coolant to leak or the engine has cracked....

Q: Code P0171. Do I need to take car to dealership to address this problem.

Hey there. It sounds like your throttle body is bad. Check to make sure it's clean and not sticking. Clean the throttle body if necessary and check for loose connections with the throttle body connectors, too. Since you said that...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...