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Home › Volvo › 1997 › S90 AW30-40 › Repair and Diagnosis › Engine Performance › System › Engine Controls - Tests W/Codes › Diagnostic Tests › DTC 436: Rear Ho2S Compensation

DTC 436: Rear Ho2S Compensation

  1. Perform a compression check on all cylinders. See ADJUSTMENTS article. Repair as necessary. If compression is okay, go to next step.
  2. Check for air leakage in intake system. Repair as necessary. If there is no air leakage in intake system, check for air leakage in exhaust system. Repair as necessary. If there is no air leakage in exhaust system, check fuel and residual pressure. Repair as necessary. If fuel and residual pressure are okay, go to next step.
  3. Turn ignition on. Squeeze hose between CP valve and intake manifold with Hose Pliers (115 8957). DTC for EVAP system can be set. Start engine and run at idle until rear HO2S starts operating. Rear HO2S starts operating a short time after rear HO2S preheating starts.
  4. Remove multi-nipple plugs. Using scan tool, voltage at rear sensor should drop to zero. Wait 30 seconds. Reinstall multi-nipple plugs. Voltage at rear HO2S should increase to about .8 volt. If voltage at rear HO2S drops to about zero volts, retest using new front HO2S. If voltage at rear HO2S does not drop to about zero volts, retest using new rear HO2S.
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