Code
P1230
SUBARU
P — Powertrain
Fuel Pump Control Unit Malfunction
AI status
Completed
Completed
100%
Causes
- Faulty fuel pump control unit/module
- Open/short in wiring between ECM, fuel pump control unit and fuel pump
- Poor or corroded connector or ground at pump or control unit
- Blown fuse or failed fuel pump relay
- Weak battery or poor battery connections reducing supply voltage
- Failed fuel pump motor (excessive load)
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated with P1230 stored
- No-start or extended cranking with little/no fuel pressure
- Intermittent stalling or unexpected engine shutdown
- Engine cranks but poor/no fuel pump prime
- Reduced engine performance or hesitation under load
- Inconsistent fuel pressure readings or pump not running when commanded
What to check
- Confirm code stored and record freeze frame data and other related codes
- Visually inspect wiring and connectors at fuel pump, fuel pump control unit/module, ECM and associated relays/fuses
- Check battery voltage and charging system health (battery terminals clean, >12.4 V at rest)
- Check fuel pump fuse(s) and relay(s) routing — swap with known-good if applicable
- Attempt to hear/verify pump prime with key ON (engine off)
- Measure fuel rail/line pressure with an appropriate gauge during key-on, cranking and running (if safe)
Signal parameters
- Battery supply at pump connector with key ON: typical ~11.5–14.5 V (model dependent)
- Control output to pump: either switched B+ or PWM command — expected to change when ECM/command active (0–100% duty cycle)
- Pump current draw while running: typically a few amps up to 10 A depending on pump and engine (measure with clamp ammeter)
- Pump resistance (static) between pump power and ground: consult manufacturer spec; significant deviation or open indicates bad pump
- Ground continuity from pump/control module to chassis: should be low resistance (
- Scan-tool parameter: fuel pump control module status/response and any communication error flags (varies by model)
Diagnostic algorithm
- Read and record DTC(s) and freeze-frame data with a capable scan tool; note vehicle conditions when code set
- Clear the code and attempt to reproduce to confirm repeatability (some faults are intermittent)
- Perform visual inspection of fuses, relays and wiring harnesses for damage, corrosion, or loose connectors (pump, control unit, PCM)
- Verify battery voltage and clean/tighten battery terminals. Repeat DTC check if voltage was marginal
- With key ON (engine OFF) verify fuel pump prime by listening and/or measuring voltage at the pump connector; if no voltage, check fuse and relay
- Backprobe the pump power and ground during key ON/cranking and while commanding pump via scan tool to observe voltage and/or PWM. Record values
- Measure fuel pressure with an appropriate gauge during key ON, cranking and engine running (if safe). Compare to spec; very low/no pressure indicates pump/power issue
- Measure pump current draw with a clamp ammeter while pump runs. Excessive current suggests internal pump fault; no current suggests open circuit
- If harness and supply are good but control signals abnormal, inspect/replace fuel pump control unit/module or its connector; confirm ECM communications and check for TSBs or software updates before replacement
- If replacing module or pump, disconnect battery and follow manufacturer procedures; after repair, clear codes and re-test to confirm proper operation
Likely causes
- Intermittent or corroded connector at fuel pump or control module
- Open/shorted harness or chafed insulation causing intermittent signal
- Failed fuel pump control unit (internal electronics)
- Low battery voltage or weak charging system during test
- Blown in-line fuse or failed relay preventing correct power to pump
Fault status
Status
P1230 — Fuel Pump Control Unit Malfunction: ECM detected abnormal or missing signal from fuel pump control unit or its output circuit is out of expected range.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email