P045D

Gas Recirculation B Control Circuit High

P045D is a generic OBD-II powertrain diagnostic trouble code: Gas Recirculation B Control Circuit High. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P045D
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on, possible limp mode)
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What P045D means

P045D is a generic SAE powertrain code that indicates the ECU has detected a high voltage condition on the Exhaust Gas Recirculation (EGR) 'B' control circuit. The 'B' designator identifies the second EGR valve or EGR circuit in systems that employ dual EGR loops — commonly found on turbocharged diesel engines and some modern petrol engines with high-pressure and low-pressure EGR circuits. A 'circuit high' fault means the signal voltage measured by the ECM/PCM on the EGR valve actuator or position sensor wire exceeds the expected upper threshold, which typically points to an open circuit, a short to supply voltage, or a failed sensor/solenoid.

The EGR system reduces NOx emissions by recirculating a metered portion of exhaust gas back into the intake manifold to lower peak combustion temperatures. When the ECU cannot properly control the 'B' EGR valve due to an out-of-range high signal, it loses the ability to regulate exhaust gas recirculation accurately. This may cause the engine to run with incorrect air/fuel mixture ratios, elevated NOx output, rough idle, reduced power, or increased fuel consumption. The fault is stored alongside an illuminated MIL (Check Engine Light) and the engine may enter a reduced-performance mode on some platforms.

P045D is closely related to P045A (EGR B circuit general), P045B (EGR B circuit range/performance), and P045C (EGR B circuit low). Unlike P045C, which typically indicates a short to ground or open sensor ground, P045D specifically flags a short to battery voltage or a broken reference/signal return path that pulls the signal wire high. Diagnosis should confirm wiring integrity and actuator resistance before condemning the EGR valve or ECM.

Common causes

Most-frequently reported root causes when P045D is logged.

  • 1
    Short to battery voltage (B+) on the EGR 'B' valve control or position sensor signal wire
  • 2
    Open circuit in the EGR 'B' valve signal return or ground wire
  • 3
    Failed EGR 'B' valve position sensor (internal short to supply)
  • 4
    Failed EGR 'B' actuator solenoid with shorted windings
  • 5
    Corroded, damaged, or water-ingressed EGR valve connector causing high-resistance or cross-wiring
  • 6
    Faulty PCM/ECM output driver for the EGR 'B' circuit (rare, diagnose last)
  • 7
    Chafed wiring harness shorting to a 12 V rail near the EGR valve or intake manifold

Symptoms drivers notice

MIL (Check Engine Light) illuminated
Reduced engine power or limp-home mode on vehicles with strict EGR monitoring
Rough idle or unstable idle due to incorrect EGR flow
Increased fuel consumption from poor combustion efficiency
Elevated NOx emissions — vehicle may fail emissions inspection
Possible black smoke or sooty exhaust on diesel applications if EGR sticks open

How to diagnose P045D

A typical diagnostic flow when this code is present.

  1. 1
    Scan for all stored and pending DTCs; note any companion EGR codes (P045A, P045B, P045C, P0400–P0409) to establish whether the fault is circuit-specific or system-wide
  2. 2
    Inspect the EGR 'B' valve wiring harness and connector for chafing, corrosion, pushed-back terminals, or visible insulation damage — pay close attention to routing near hot exhaust components
  3. 3
    With the ignition on (engine off), measure the signal voltage at the EGR 'B' valve connector: a reading at or near battery voltage (12–14 V) on a low-voltage sensor signal wire confirms a short to B+
  4. 4
    Disconnect the EGR 'B' valve connector and re-measure the signal wire at the harness side; if voltage drops to zero, the short is within the valve/sensor itself; if voltage persists, the short is in the harness or PCM
  5. 5
    Measure EGR 'B' solenoid/actuator coil resistance with an ohmmeter; compare to manufacturer specification — a reading significantly below spec indicates a shorted winding
  6. 6
    Clear the code and perform a drive cycle with live data monitoring of EGR 'B' valve position and commanded duty cycle to confirm normal operation after any repairs
  7. 7
    If all wiring and the valve test good, perform a PCM pin-out voltage test per the vehicle-specific wiring diagram before suspecting an ECM fault

Vehicles where we've handled P045D

Platforms in our catalogue with confirmed P045D coverage.

AUDI A4 20D

Related powertrain codes

Frequently asked questions

Can I drive with a P045D code?

Short-term driving is generally possible if there are no drivability issues, but it is not recommended. If the engine has entered limp mode or is running roughly, you should have it diagnosed promptly. Continued driving with a faulty EGR circuit can increase NOx emissions and may cause carbon build-up in the intake manifold over time.

Is P045D the same fault as P045C?

No. P045C (EGR B Circuit Low) flags a signal voltage below the expected range — typically a short to ground or open signal wire. P045D (EGR B Circuit High) flags a signal voltage above the expected range — typically a short to battery voltage or a broken ground/return path. Both affect the same 'B' EGR circuit but require different diagnostic approaches.

Which vehicles are most likely to set P045D?

P045D is most commonly seen on turbocharged diesel engines (Euro 5/6 and later) fitted with dual EGR circuits — for example, BMW N47/N57, Ford Duratorq, Volkswagen TDI, and Renault dCi engines — as well as on some modern direct-injection petrol engines with high-pressure EGR. Vehicles with a single EGR valve typically only use the 'A' circuit codes.

Will replacing the EGR valve fix P045D?

Only if the EGR 'B' valve's internal position sensor or actuator coil is confirmed to be shorted to supply voltage. In many cases the root cause is a wiring harness fault (chafed wire, corroded connector) rather than the valve itself. Always diagnose the circuit electrically before replacing parts to avoid an unnecessary and costly repair.

Disabling P045D in software

RaceTune can permanently disable P045D — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

ECUs with a P045D disable in our catalogue

Confirmed coverage from our recipe database — we support many more families. Upload your file and our identifier will match it automatically.

  • Bosch EDC17C74 verified 1 software version

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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