Fuel Pump Secondary Circuit Malfunction
The P1242 code indicates a malfunction in the secondary circuit of the fuel pump. This manufacturer-specific code is triggered when the Powertrain Control Module (PCM) detects an electrical anomaly in the control circuit of the fuel pump relay or module. The PCM continuously monitors the feedback signal from the secondary circuit to ensure the pump receives proper power under engine demand conditions. If voltage or resistance deviates from the manufacturer's specified parameters, this fault code is set.
01. Most Common Causes
- Damaged or stuck fuel pump relay
- Blown or open fuel pump circuit fuse
- Short or open in the secondary circuit wiring
- Corroded electrical connections or bent pins in the harness
- Internal failure in the PCM
02. Symptoms You Will Notice
- Engine cranks but does not start
- Engine stalls or hesitates during acceleration
03. Step-by-Step Diagnosis
Check fuel pump fuse and relay for continuity and proper operation
Inspect wiring and connectors for damage, corrosion, or loose pins
Test fuel pump driver module (FPDM) per manufacturer procedure
Verify fuel pump operation and fuel pressure
If all else fails, test PCM for internal fault
1. Frequently Asked Questions
Is it safe to drive?▼
No, driving with this code is not recommended as it can cause the engine to stall or fail to start, leading to a potential safety hazard.
How much does it cost to fix?▼
Repair costs typically range from $150 to $600, depending on the root cause (e.g., relay, wiring, or module replacement).