OBD-II Fault Code

P1304: EGR Calibration High

Meaning, symptoms, likely causes, diagnostic checks and repair guidance for P1304.

System family

Powertrain

Manufacturer-specific

Repair category

EGR / emissions

Use this category to narrow your checks before replacing parts.

Severity

Medium

Severity is a general guide. Confirm with scan-tool data and vehicle symptoms.

What P1304 usually means

EGR Calibration High.

Common symptoms

Check Engine light; Poor drivability or reduced fuel economy depending on fault

Likely causes

Stuck EGR valve; Blocked EGR passage; Vacuum/control solenoid fault; DPFE/position sensor fault; High signal voltage; Open ground; Short to voltage; Failed sensor

Diagnostic checks

Scan all modules and record freeze-frame data before clearing codes; Check battery voltage and related fuses; Command EGR operation if supported; Inspect passages for carbon blockage; Check sensor ground and signal circuit for short to voltage

Repair guidance

Clean carbon passages, repair vacuum/control circuit, replace stuck valve or failed sensor after testing; Repair ground/signal circuit or replace confirmed faulty sensor

Verification after repair

Clear code, road-test through the same drive condition, then rescan

Note: Confirm vehicle make/model/year because manufacturer-specific codes can vary; Manufacturer-specific: confirm definition and test steps in the vehicle service manual. A DTC identifies a circuit or system condition, not always the failed part.