What Does P1237 Mean?
DTC P1237 indicates a malfunction in the fuel pump speed primary control circuit, similar to P1232 but may represent a different fault condition or detection method within the same circuit. The PCM has identified an electrical anomaly in the signal that controls how fast the fuel pump runs, preventing proper fuel pump speed modulation based on engine demand.
Common Causes
30%
Faulty fuel pump driver module with degraded speed control output
25%
Intermittent open in the primary speed control wiring
20%
PCM fuel pump control driver circuit degradation
15%
Connector terminal back-out or corrosion at FPDM
10%
Electromagnetic interference affecting the speed control signal
Diagnostic Steps
1
Compare freeze frame data for P1237 vs. any concurrent fuel pump codes to determine if the fault is consistent or intermittent.
2
Use an oscilloscope to monitor the PWM signal from the PCM to the FPDM on the primary speed control wire — verify proper duty cycle modulation.
3
Inspect the FPDM connector for backed-out pins, corrosion, or loose fit. Perform a wiggle test on the connector while monitoring the signal.
4
Verify the FPDM ground is clean and tight with less than 0.1 ohms resistance to the battery negative terminal.
5
If the FPDM and wiring check good, monitor the PCM output at the PCM connector to verify the control signal is being generated.
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
DTC P1237 indicates a malfunction in the fuel pump speed primary control circuit, similar to P1232 but may represent a different fault condition or detection method within the same circuit. The PCM has identified an electrical anomaly in the signal that controls how fast the fuel pump runs, preventi...
The most common cause of P1237 (Fuel Pump Speed Primary Circuit Malfunction) is: Faulty fuel pump driver module with degraded speed control output
Typical repair costs for P1237 range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Improper fuel pump speed control can cause inconsistent fuel pressure, leading to drivability issues ranging from surging at idle to hesitation under acceleration. Extended operation may cause premature pump failure.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1237 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel Delivery
Difficulty
Type
Manufacturer
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