2000 Toyota Rav4 Engine light on

Tiny
STARWISHER115
  • MEMBER
  • 2000 TOYOTA RAV4
  • 4 CYL
  • AWD
  • AUTOMATIC
  • 64,000 MILES
I have cleaned the MAF & replaced the air filter, disconnected the battery to reset the computer, light came back on about 10 miles later. Car is running better since the cleaning (low idle when first started, little acceleration going uphill). How do I find out if it's the sparkplugs, O2 sensor, needs new MAF, vacuum leak or something else? Seems there are a lot of possibiltiies to cause this. Any ideas?
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Thursday, August 13th, 2009 AT 7:03 PM

3 Replies

Tiny
KHLOW2008
  • EXPERT
Hi starwisher115,

When the MIL indicates, trouble code(s) would be stored in the Power Control Module. You would need to retrieve the trouble code to understand what is cauing the MIL to show.

Get a free scan done at Autozone and let me know the exact trouble code so I can assit in solving the problem.
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Thursday, August 20th, 2009 AT 2:08 PM
Tiny
STARWISHER115
  • MEMBER
I had the codes read & got PO171. Have also noticed turning on the A.C. Really affects the acceleration & idle.
I didn't remove the MAF when I cleaned it, Would that have made a difference?
Is there any site that would give me step by step directions on replacing the MAF myself?
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Thursday, August 20th, 2009 AT 5:49 PM
Tiny
KHLOW2008
  • EXPERT
Here are the description of the code and diagnostic procedures.

DTC P0171 OR P0172: SYSTEM TOO LEAN/RICH (EXCEPT CALIF. EMISSIONS)
Circuit Description
Fuel trim refers to feedback compensation value compared against basic injection time. Fuel trim
includes short-term and long -term fuel trim.
DTC P0171 is set when fuel trim is driven rich beyond a certain value. Possible causes are:
Air induction system malfunction.
Fuel injector restricted.
Defective Manifold Absolute Pressure (MAP) sensor.
Defective Engine Coolant Temperature (ECT) sensor.
Improper fuel pressure.
Exhaust system leak.
Heated oxygen sensor No. 1 circuit is open or shorted.
Defective heated oxygen sensor No. 1.
Defective ECM.
DTC P0172 is set when fuel trim is driven lean beyond a certain value. Possible causes are:
Fuel injector restricted or leaking.
Defective Manifold Absolute Pressure (MAP) sensor.
Defective Engine Coolant Temperature (ECT) sensor.
Ignition system malfunction.
Improper fuel pressure.
Exhaust system leak.
Heated oxygen sensor No. 1 circuit is open or shorted.
Defective heated oxygen sensor No. 1.
Defective ECM.

Diagnostic Aids
When DTC P0171 is recorded, actual air fuel ratio is too lean. When DTC P0172 is recorded, actual
air fuel ratio is too rich. If vehicle runs out of fuel, DTC P0171 will be set. Using scan tool, read
freeze frame data. Freeze frame records engine conditions when malfunction is detected.
Diagnosis & Repair
CAUTION: If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction.
NOTE: Heated oxygen sensor No. 1 refers to oxygen sensor closest to engine block. Heated oxygen sensor No. 2 refers to oxygen sensor farthest
from engine block.
1. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
2. Check fuel injectors. If problem exists, repair as necessary. If problem does not exist, go to next step.
3. Check Manifold Absolute Pressure (MAP) sensor and Engine Coolant Temperature (ECT) sensor. If problem exists, replace appropriate component. If problem does not exist, go to next step.
4. Check spark and ignition system. If problem exists, repair as necessary. If problem does not exist, go to next step.
5. Check fuel pressure. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
6. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, go to next step.
7. Connect scan tool to Data Link Connector (DLC) No. 3. Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Let engine idle. Using scan tool, monitor heated oxygen sensor No. 1 output voltage. Voltage should alternate repeatedly from less than.4 volt to more than.5 volt. If voltage is as specified, go to step 9. If voltage is not as specified, go to next step.
8. Check for open or short in wiring between ECM and heated oxygen sensor No. 1. If problem exists, repair wiring as necessary. If problem does
not exist, replace heated oxygen sensor No. 1.
9. Perform test drive confirmation, then go to next step.
10. Clear and recheck for DTCs. If DTC P0171 and/or P0172 are displayed again, replace ECM. If neither DTC P0171 nor P0172 is displayed again, go to next step.
11. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.

MAF is plugged into air cleaner housing and can be remove after taking out the holding bolts. No tricks in a straight forward job.
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Saturday, August 22nd, 2009 AT 9:19 AM

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