P0233: Fuel Pump Secondary Circuit Intermittent
Intermittent engine stalling, hard starting, hesitation, or no-start conditions.
Overview
P0233 indicates an intermittent fault in the fuel pump secondary circuit where the powertrain control module detects irregular voltage or continuity in the circuit supplying the fuel pump.
Common Symptoms
- Illuminated Check Engine Light
- Engine may stall or hesitate under load
- Difficulty starting or extended cranking
- Unexpected engine shut-off
- Intermittent loss of power
Most Common Causes
Relay may intermittently fail to provide correct voltage to the fuel pump circuit.
Loose, corroded, or broken wires/connectors cause intermittent voltage or continuity issues.
Some vehicles use a dedicated control module that may fail or lose proper communication intermittently.
PCM output driver may be intermittently shorted to ground or defective.
Less common cause; intermittent internal electrical faults in the pump can trigger the code.
Diagnostic Steps
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Retrieve and confirm stored and pending codes with OBD-II scanner and document freeze-frame data.Expected: Code P0233 present without conflicting primary circuit codes.Interpretation: Verifies the intermittent secondary circuit issue is current and not transient.
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Visually inspect fuel pump relay, wiring harness, connectors, and grounds for damage or corrosion.Expected: Secure, clean connections and no damaged insulation.Interpretation: Bad connections or harness damage can cause intermittent loss of continuity triggering the code.
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Test or swap the fuel pump relay with a known good relay.Expected: Consistent power delivery to fuel pump circuit.Interpretation: Failure to maintain stable voltage suggests relay is a likely cause.
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Measure voltage and continuity at the fuel pump connector with ignition ON and engine running.Expected: Stable voltage near battery voltage without intermittent drops.Interpretation: Fluctuating measurements indicate wiring, connection, or control module issues.
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Check PCM fuel pump control output with scan tool/oscilloscope for intermittent signals.Expected: Consistent PWM or voltage signal from PCM/FP control module.Interpretation: Irregular output suggests PCM or control module driver fault.
Repair Solutions
Often resolves intermittent relay contact issues.
Repair costs vary with extent of wiring damage.
Requires professional diagnosis and VIN-matched programming.
Less common, typically after other causes are ruled out.
Common Misdiagnoses
Avoid these common diagnostic mistakes:
- Assuming a bad fuel pump without checking relay and wiring first
- Confusing P0233 with primary fuel pump circuit codes like P0230
- Attributing symptoms solely to low battery
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