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B1342 Manufacturer-specific Basic entry

ECU Is Defective

Updated 2026-10-02 · Body (manufacturer-specific)

Severity
Low
Typical repair cost
60 – 500 EUR
System
Body

This is a manufacturer-specific code. Its exact meaning can differ between makes; the definition below follows the most common usage.

What it means

B1342 is defined as "ECU Is Defective". the body control module stores it when the monitored condition for this component or system is outside the limits programmed by the manufacturer.

This entry is compiled automatically from the standard definition and typical diagnostic practice for this type of fault. A detailed, reviewed article is in preparation.

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Symptoms

  • The affected function (lighting, locking, windows, seats, climate or restraint) does not work or works intermittently
  • Warning light or message on the instrument cluster
  • Possible battery drain if a module stays awake

Common causes

  1. ECU Is Defective worn, contaminated or out of calibration
  2. Mechanical problem in the system the sensor measures
  3. Air, vacuum or exhaust leak influencing the reading
  4. Wrong or low-quality replacement part
  5. Wiring resistance causing a small voltage offset

How to diagnose

  1. Compare the live ECU Is Defective reading with a known-good value or a second sensor at idle and at 2500 rpm
  2. Check for air, vacuum or exhaust leaks that could skew the reading
  3. Inspect the component for contamination and clean it if the design allows
  4. Verify the part number is correct for the engine
  5. Replace the ECU Is Defective if the reading remains out of specification

Frequently asked questions

Can I keep driving with B1342?

Yes. The fault does not affect safety or driveability, but it will keep the warning light on and may fail an inspection.

Will clearing B1342 fix it?

No. Clearing only erases the stored code; it returns as soon as the monitor runs again unless the cause is repaired.

Related codes

C1137

Nearby codes in this group