What Does P045C Mean?
The EGR 'B' control circuit voltage is below the PCM's minimum expected threshold. This low circuit condition indicates the control solenoid or motor winding may be shorted, the control wire may be grounded, or there is a low-resistance fault in the circuit. The PCM cannot properly command the EGR 'B' valve. The driver will see a check engine light and may notice idle quality changes.
Common Causes
35%
Control wire shorted to ground in the EGR 'B' valve harness
30%
Internally shorted EGR 'B' valve motor or solenoid coil
20%
Water intrusion or corrosion in the valve connector
10%
PCM output driver pulled low by the short circuit load
5%
Harness damage from exhaust heat melting insulation
Diagnostic Steps
1
Disconnect the EGR 'B' valve connector and measure the solenoid/motor resistance. Compare to specifications. A significantly low reading indicates a turn-to-turn short in the coil.
2
With the valve disconnected, check each harness wire for resistance to ground. Should read OL (open). Any measurable low resistance points to a wire shorted to ground.
3
Visually trace the EGR 'B' valve wiring for heat damage, especially where the harness runs near the exhaust manifold, turbocharger, or EGR pipe. Melted insulation is a common finding.
4
Inspect the connector for moisture and corrosion. EGR components are in extremely hot areas and experience significant thermal cycling that can degrade seals.
5
If the valve and wiring test good, verify the PCM output by measuring the control voltage at the PCM connector with the valve disconnected and key on.
Estimated Repair Cost
$150 - $550
Parts + labor, varies by vehicle and location
The EGR 'B' control circuit voltage is below the PCM's minimum expected threshold. This low circuit condition indicates the control solenoid or motor winding may be shorted, the control wire may be grounded, or there is a low-resistance fault in the circuit. The PCM cannot properly command the EGR '...
The most common cause of P045C (Exhaust Gas Recirculation "B" Control Circuit Low) is: Control wire shorted to ground in the EGR 'B' valve harness
Typical repair costs for P045C range from $150 to $550, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Generally safe to drive for short distances. Without proper EGR control, the engine may idle roughly and NOx emissions will increase. Avoid sustained heavy load until repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P045C to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
EGR / Emissions System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
