P1236 Fuel Pump Secondary Circuit Low
The P1236 code indicates that the powertrain control module (PCM) has detected abnormally low voltage or resistance in the fuel pump secondary circuit. This circuit typically controls the fuel pump drive module (FPDM) or fuel pump control module, which manages pump speed via pulse-width modulation (PWM). The 'low' condition may refer to low voltage on the FPDM feedback circuit to the PCM or a weak PWM command signal. In Ford vehicles, this code is directly linked to the electronic fuel pump control system that uses a separate module to regulate fuel pressure.
01. Most Common Causes
02. Symptoms You Will Notice
- Engine cranks but does not start
- Engine stalls or hesitates during acceleration
- Reduced fuel economy
- Check Engine Light illuminated
03. Step-by-Step Diagnosis
Scan for codes and verify P1236 is present
Inspect wiring and connectors between PCM and FPDM for damage or corrosion
Test FPDM power and ground circuits with a multimeter
Check fuel pump current draw and compare to specifications
If wiring and pump are good, test/replace FPDM
As a last resort, test PCM for proper output signals
1. Frequently Asked Questions
Is it safe to drive?▼
No, driving with P1236 is not recommended. The vehicle may stall unexpectedly or fail to start, posing a safety risk.
How much does it cost to fix?▼
Repair costs typically range from $200 to $800, depending on whether the FPDM, fuel pump, or wiring needs replacement.