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U064E Lost Communication With EGR Cooler Bypass Position Sensor Bank 1

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modeNo

Many diesels steer recirculated exhaust around the EGR cooler while the engine is cold and through it once warm, using a bypass flap with its own position sensor. CARB 1968.2 (f)(6.2.5) requires the cooler system to be checked for poor cooling, and that check only makes sense if the controller knows the flap position. U064E is set when this sensor on bank 1 is a digital part and its data no longer arrives. No manufacturer documents U064E publicly, and the published code lists show no separate bank 2 counterpart. An analog sensor would report P2492 to P2496 instead, and a learned end stop outside its limit is P24C4. While the position is unknown, the cooler performance monitor cannot run; warm-up emissions may rise slightly.

Likely causes

Wiring to the cooler bypass actuator damaged by heat or vibration

Corroded or loose connector at the bypass actuator

Position sensor in the bypass actuator failed

Engine controller input fault

Symptoms

MIL on
EGR cooler monitor not completed
Usually no change in driving behaviour

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€60–700

Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

egr cooler bypass position sensor bank 1vehicle bus wiring

References: law.cornell.edu, en.wikipedia.org, en.wikipedia.org.