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DTC 71

EGR System Malfunction (Only for Califor-

nia spec.)

CIRCUIT DESCRIPTION

The EGR system, recirculates exhaust gas, which is controlled to the proper quantity to suit the driving condi-

tions, into the intake air mixture to slow down combustion, reduce the combustion temperature and reduce NOx

emissions. The amount of EGR is regulated by the EGR vacuum modulator according to the engine load.

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Under the following conditions, EGR is cut to main-

tain driveability.

 Engine coolant temp. below 35C (95F)

 During deceleration (throttle valve closed)

 Light engine load (amount of intake air very small)

 Engine idling

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Code No. Diagnostic Trouble Code Detecting Condition Trouble Area

EGR gas temp. is 70C (158F) or below for 1  4 min.

under conditions (a) and (b). (2 trip detection logic)*

(a) Engine coolant temp: 60C (140F) or more

(b) EGR operation possible. (EX. Electronic Con-

trolled Transmission in D position, A/C ON, 60 mph

(96 kn/h), Flat road).

Open in EGR gas temp. sensor circuit

EGR or TVV vacuum hose disconnected

valve stuck

Clogged EGR gas passage

ECM

*: See page EG–331.

EG–408

–ENGINE TROUBLESHOOTING CIRCUIT INSPECTION

Toyota 3VZ–FE User Manual

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