OBD Guide
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P0378

Timing Reference High Resolution Signal B Intermittent/Erratic Pulses

P0378 is an OBD-II diagnostic trouble code meaning: Timing Reference High Resolution Signal B Intermittent/Erratic Pulses. Common causes: unstable contact in the sensor connector (oxidation, weakening), damage to the wiring (chafing, short circuit during vibration). Estimated repair cost: $22–111.

Severity
🔴 High
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$22–111 (est.)

Symptoms

  • Unstable engine operation with unpredictable failures
  • Intermittent misfires in different cylinders
  • The engine may stall while driving
  • Check Engine Light Is On (Intermittent)
  • Difficulty starting after a short stop

Causes

  • Unstable contact in the sensor connector (oxidation, weakening)
  • Damage to the wiring (chafing, short circuit during vibration)
  • Partially damaged drive disk
  • Failing sensor
  • Electromagnetic interference from neighboring circuits

How to Fix

  1. Read the error codes, pay attention to the intermittent nature (intermittent)
  2. Inspect and clean the sensor connector, check the fixation
  3. Check the wiring with the engine running (move the harness slightly to see if the error changes)
  4. Check the air gap and the condition of the drive disk
  5. Replace sensor as most likely cause of intermittent fault
  6. Check signal cable shielding

Related codes

P0374P0377P0335P0320P0336

Error P0378 by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the P0378 code mean?

P0378 is an OBD-II diagnostic trouble code that indicates: Timing Reference High Resolution Signal B Intermittent/Erratic Pulses

What causes a P0378 error code?

The most common causes of P0378 include: Unstable contact in the sensor connector (oxidation, weakening); Damage to the wiring (chafing, short circuit during vibration); Partially damaged drive disk; Failing sensor.

How do I fix a P0378 diagnostic trouble code?

To fix P0378: Read the error codes, pay attention to the intermittent nature (intermittent). Inspect and clean the sensor connector, check the fixation. Check the wiring with the engine running (move the harness slightly to see if the error changes). For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P0378?

Do not drive — repair immediately

How much does it cost to fix P0378?

The estimated repair cost for P0378 is $22–111. Actual cost depends on your vehicle, location, and labor rates.

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