The P1236 code on your 2022 Lincoln Nautilus indicates a high voltage condition in the fuel pressure regulator control circuit. This Ford-specific code means the PCM is detecting higher than expected voltage in the circuit controlling fuel rail pressure on your Nautilus's turbocharged 2.0L or 2.7L engine.
Understanding P1236 on Lincoln Nautilus
The fuel pressure regulator control circuit uses a pulse-width modulated signal from the PCM to control fuel rail pressure based on engine demands. Code P1236 sets when the circuit voltage exceeds the calibrated threshold, indicating a potential short to power or feedback issue in the regulation system. This differs from P1235, which indicates low voltage.
Common Symptoms
- Check engine light on
- Excessive fuel consumption
- Strong fuel odor from tailpipe
- Rough running or surging
- Black smoke from exhaust under acceleration
- Possible hard starting when hot
Primary Causes
- Short to power in regulator control wiring
- Damaged wiring harness contacting positive voltage source
- Internal short in fuel pressure regulator solenoid
- Corroded connector causing feedback voltage
- Aftermarket wiring modification interference
- PCM driver circuit failure
Diagnostic Procedure for 2022 Nautilus
Begin diagnosis with the fuel pressure regulator connector disconnected. Measure voltage at the PCM control wire with key on, engine off - it should show minimal voltage. If voltage is present with connector disconnected, trace the circuit for shorts to power. Inspect wiring harness routing for chafing against positive battery cables or other power sources. Test regulator solenoid for internal shorts by measuring resistance to both ground and power.
Repair Solutions
Repair any wiring shorts by replacing damaged sections with proper gauge wire and connectors. If the regulator solenoid has an internal short, replace the fuel pressure regulator or high-pressure fuel pump assembly as applicable. Ensure proper routing of repaired wiring away from potential short sources. Clear codes and verify actual fuel pressure matches commanded pressure during test drive.