P005E — Turbocharger/Supercharger Boost Control "B" Supply Voltage Circuit Low

powertrain (engine/transmission)

Is it safe to drive?

Reduced boost control; repair promptly P005E can leave boost control "B" operating at an incorrect voltage, causing underboost, unstable boost, or reduced engine output. Avoid heavy acceleration or sustained high-load driving until the circuit is repaired. If boost becomes excessive, the engine misfires badly, or the vehicle cannot maintain safe speed, stop safely and seek service.

Typical symptoms

The check engine light illuminates and the OBD2 system stores P005E.
The engine may produce less boost than expected, especially during moderate or high-load acceleration.
A boost gauge may read low, fluctuate unexpectedly, or fail to respond when boost is requested.
The boost-control solenoid or actuator may click repeatedly or stop responding to control commands.
Some vehicles enter a reduced-power or limp mode when P005E is active.

Common causes

P005E commonly results from an open or high-resistance supply wire feeding the turbocharger/supercharger boost control "B" circuit.
A corroded, loose, backed-out, or heat-damaged connector at the boost-control solenoid or actuator can create the low-voltage condition.
A failed electrically controlled boost-control component B may draw excessive current and pull its supply voltage below the diagnostic threshold.
A blown fuse or defective relay in the boost-control B power path can interrupt or destabilize the supply voltage.
Low battery or alternator output can activate P005E when the control circuit receives insufficient system voltage.
A poor engine, chassis, or component ground can make the voltage measured at the boost-control B circuit appear abnormally low.

How to diagnose with an OBD scanner

Confirm P005E and related information Connect an ELM327-based OBD2 scanner, AIScanAuto, or another compatible scanner and confirm that P005E is current. Review freeze-frame, pending, and permanent codes for evidence of low system voltage, relay, or communication faults. If the scanner supports live electrical data, compare it with a service specification when available.
Inspect the boost-control B circuit Using the vehicle wiring diagram, locate boost-control component B and inspect its connector, supply wire, and nearby grounds. Look for burned terminals, green corrosion, pushed-back pins, water intrusion, chafing, or damage near the heat-affected turbocharger area.
Measure voltage under load With the ignition commanded on and the boost-control component connected, measure supply voltage at its connector. Back-probe both terminals so the meter does not distort the circuit, then perform a voltage-drop test while the component is active. Repair excessive resistance before condemning the component.
Check power and ground sources Verify the applicable fuse, relay contacts, battery state of charge, and alternator output. Confirm that voltage remains stable at the boost-control B connector and that voltage from the component ground to battery negative stays low. P005E should not be attributed to a weak component while its supply is unstable.
Repair and verification Repair the open wire, terminal, fuse, relay, ground, or failed boost-control component as the test results require. Clear P005E with the OBD2 scanner, then verify commanded versus actual boost, check for new codes, and confirm that the supply voltage remains within specification during a full boost request.

Approximate repair cost

A typical independent-shop estimate for diagnosing and repairing P005E is roughly USD 180-750, depending on whether the fault is a wiring or connector repair, a relay or fuse issue, or a failed boost-control solenoid or actuator. These figures are estimates and vary by region.

Common questions

What does code P005E mean?

P005E means the control module detected that the supply voltage to turbocharger or supercharger boost control "B" was below the calibrated operating range.

Can a damaged wire cause P005E?

Yes. Corrosion, a loose terminal, chafing, or an open supply wire can prevent boost-control component B from receiving the voltage required for proper operation.

Should the boost-control solenoid be replaced first?

Not necessarily. Supply voltage, voltage drop, connector condition, fuses, relays, and grounds should be tested before replacing the solenoid or actuator based on P005E alone.

Is it safe to drive with P005E stored?

P005E does not always create an immediate hazard, but incorrect boost control can cause major underboost, unstable power, or limited-mode operation. Repair it promptly and avoid heavy loading until diagnosed.

When the engine control module notices that the voltage feeding the turbocharger or supercharger boost regulator on circuit B has fallen below factory specifications, it logs OBD2 code P005E. In plain language: the supply voltage for boost control circuit B is reading far too low—essentially sitting near ground potential instead of the higher operating voltage the computer expects. This falls under the powertrain category, which means it affects the engine and transmission management systems.

A "circuit low" condition indicates one of several possibilities: the wiring may be shorted directly to ground, insulation could be worn away and the bare wire is touching metal, the supply voltage feed may have been interrupted entirely, or a defective component is dragging the signal down. The ECM arrives at this conclusion by comparing live sensor readings against calibrated thresholds, typically across multiple drive cycles before confirming a genuine fault. When the module sets P005E, it also saves a freeze frame—a snapshot recording RPM, engine load, coolant temperature, and vehicle speed at the exact moment the failure occurred. Reviewing that data first often points directly to the root cause.

Common Symptoms of P005E

Check Engine Light illuminated on the dashboard
Noticeable loss of engine power, especially under acceleration
Vehicle enters limp-home mode, severely limiting RPM and throttle response
Black smoke billowing from the exhaust during acceleration
Unusual whistling or high-pitched noise coming from the engine bay
Increased oil consumption due to boost system stress

What Causes P005E?

Signal wire shorted to ground from chafed or damaged insulation
Missing supply voltage reaching the boost control circuit connector
Faulty boost control solenoid or actuator pulling the circuit low
Stuck or sluggish wastegate operation
Worn or damaged turbocharger unit
Leaking vacuum lines or actuator hoses
Malfunctioning boost pressure sensor
Boost leak in intercooler piping, cracked hoses, or loose clamps

How to Diagnose P005E

Connect an OBD2 scanner, retrieve stored P005E codes, and record the freeze frame data—this reveals exactly what the engine was doing when the fault triggered.
Check for any related diagnostic trouble codes; secondary codes often expose the true underlying problem. Research manufacturer TSBs for your specific make and model—many P0xxx codes have documented factory fixes or software updates available through the manufacturer site or NHTSA database.
Perform a thorough visual inspection of the wiring harness and connectors feeding the turbocharger or supercharger boost control circuit. Look for damaged insulation, corrosion, loose pins, or obvious chafing where wires rub against metal brackets.
Measure supply voltage at the boost control connector first, then check resistance from the signal wire to ground. A reading near zero ohms confirms a short to ground in the harness.
Pressure-test the intake system for boost leaks—cracked intercooler hoses and loose clamps represent the most frequently encountered cause of erratic boost behavior.
Use a scanner to command the boost solenoid and physically verify wastegate or actuator movement.
Clear the code, complete a drive cycle matching the freeze frame conditions, and confirm P005E does not reappear.

Repair Options for P005E

Replace boost control solenoid or actuator: $200–$600
Repair boost leak (hoses, clamps, intercooler): $100–$400
Turbocharger replacement: $1,200–$3,500

How Much Does It Cost to Fix P005E?

The final bill depends entirely on which part has actually failed. At independent repair shops using standard labor rates, typical P005E-related repairs break down as follows: solenoid or actuator replacement runs $200–$600, addressing boost leaks in the intercooler system costs $100–$400, and full turbocharger replacement—which is rarely necessary—ranges from $1,200–$3,500. Overall, expect to spend somewhere between $100 and $3,500 to resolve this code. Proper diagnosis before purchasing parts prevents wasted money; the most expensive repair scenario is almost never the first place to look.

Can You Drive with P005E?

The vehicle will likely be running in reduced-power mode with no boost available. Continuing to drive aggressively risks engine overheating and catastrophic turbocharger failure—a repair that far exceeds the cost of addressing the original fault. Drive minimally and seek diagnosis promptly.