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Home >> Suzuki >> 2001 >> Vitara JS, 4D Utility, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0171: Total Fuel Trim Is Greater Than Allowed Specification, Or DTC P0172: Total Fuel Trim Is Less Than Allowed Specification >> Diagnosis & Repair Procedure
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Diagnosis & Repair Procedure

  1. Perform DTC CONFIRMATION TEST . If DTC P0171 or P0172 is set, go to next step. If DTCs P0171 and P0172 are not set, problem is intermittent. System is okay at this time. See TROUBLE SHOOTING - NO CODES article.
  2. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES . If DTCs other than DTC P0171 or P0172 is set, repair those DTCs first. If no other DTC is set, go to next step.
  3. Inspect intake and exhaust systems for leaks. If any leaks are detected, repair as necessary and go to DTC CONFIRMATION TEST . If intake and exhaust systems are okay, go to next step.
  4. Check fuel pressure. See CIRCUIT TEST B-3: FUEL PRESSURE INSPECTION under CIRCUIT TESTS in BASIC DIAGNOSTIC PROCEDURES article. Repair as necessary and go to DTC CONFIRMATION TEST . If fuel pressure is within specifications, go to next step.
  5. Check fuel injectors operation. See CIRCUIT TEST B-1: FUEL INJECTOR CIRCUIT INSPECTION under CIRCUIT TESTS in BASIC DIAGNOSTIC PROCEDURES article. Repair as necessary and go to DTC CONFIRMATION TEST . If fuel injectors are okay, go to next step.
  6. Check fuel lever sensor operation. See DTC P0461: FUEL LEVEL SENSOR CIRCUIT PERFORMANCE PROBLEM . Repair as necessary and go to DTC CONFIRMATION TEST . If fuel level sensor is okay, go to next step.
  7. Check MAF sensor circuit operation. See DTC P0101: MASS AIR FLOW (MAF) SENSOR CIRCUIT PERFORMANCE PROBLEM . Repair as necessary and go to DTC CONFIRMATION TEST . If MAF sensor circuit is okay, go to next step.
  8. Check ECT sensor circuit operation. See DTC P0125: INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP OPERATION . Repair as necessary and go to DTC CONFIRMATION TEST . If ECT sensor circuit is okay, go to next step.
  9. Check HO2S No. 1 sensor circuit operation. See DTC P0131: HO2S NO. 1 CIRCUIT, LOW INPUT, OR DTC P0132: HO2S NO. 1 CIRCUIT, HIGH INPUT . Repair as necessary and go to DTC CONFIRMATION TEST . If HO2S No. 1 sensor circuit is okay, replace PCM and go to DTC CONFIRMATION TEST .
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