OBD-II Diagnostic Trouble Code
P1248 — Injection Timing Control Circuit Performance
P1248 is a manufacturer-specific code that commonly means the ECM sees injection timing that does not follow its command, usually on engines with an electronically controlled injection pump timing actuator or solenoid. The actual timing feedback stayed outside the expected window. Meaning can vary by OEM.
Severity 4/5
Truck-relevant
Stop within 50 mi
Severity
Stop within 50 mi
Injection Timing Control Circuit Performance
Code
P1248
Category
Powertrain
Subsystem
Fuel
Truck-relevant
Yes
What this means for truckers
Stop within ~50 miles on a Cummins X15, Detroit DD15, PACCAR MX-13. Driving longer risks damaging adjacent components (turbo housing, head gasket, aftertreatment) and turning a $300 fix into a $3,000 fix.
Before you replace parts — try this first
P1248 on the Fuel system is most often sticking timing control solenoid or timing piston in the injection pump — not a dead part. On commercial diesels especially, work these in order before spending money on parts:
- Confirm the symptoms. Match what your truck is doing to the Symptoms section below. If the code is set but the symptoms are not there, clear the code and re-test after a drive cycle — it may not return.
- Clean and dry the sensor connector. Water, road salt, or oil seeping into a connector is the #1 fake sensor failure. Disconnect, look for green corrosion or moisture, spray with electrical contact cleaner, dry, reseat. Many faults clear here for $0.
- Inspect the wiring harness. Trace the wire from the sensor toward the ECM — look for chafing against the engine block, melted insulation near the turbo or exhaust, or pinch points where a clamp has rubbed through.
- Test the sensor before swapping it. Most Common Causes (below) list the expected voltage or resistance range — a $20 multimeter saves a $300 sensor swap that does not fix the problem.
- Only then, replace the part. Use the OEM or a tier-1 aftermarket. Cheap sensors throw the same code in two weeks.
Symptoms
Low power, poor fuel economy, hard starting, extra smoke (white when cold, black under load), louder combustion knock and possible derate. A check-engine light is normal.
Common causes
- CommonSticking timing control solenoid or timing piston in the injection pump ($300–$1200)
- OccasionalFaulty timing feedback sensor or wiring ($150–$500)
- OccasionalLow fuel supply pressure or air in the fuel ($100–$500)
- OccasionalWorn injection pump ($1500–$4000)
- RareECM fault ($500–$2000)
How to fix
Compare commanded and actual timing with a scan tool
When to use: First step
Check fuel supply pressure, filters and for air in the fuel
When to use: When timing is erratic
Test the timing solenoid and feedback sensor circuits
When to use: When fuel supply is good
Repair or replace the injection pump
When to use: When the pump timing mechanism is confirmed faulty
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
- → Browse all DTC trouble codes
- → Decode a VIN to check codes for your truck
- → Owner-operator maintenance guides
- → P1213 — Fuel Pressure Relief Valve
- → P1228 — Fuel Pump Speed Control Circuit
- → P1229 — Fuel Heater Circuit
- → P1241 — Engine Control Module Switch Sensing Voltage Too Low
- → P1249 — Fuel Injection Pressure Out of Tolerance
Frequently Asked Questions
Can I drive with code P1248?
Drive with caution. P1248 is severity 4 — stop within ~50 miles. Most commercial diesel codes at this severity (turbo, fuel rail, transmission solenoid) can damage adjacent expensive components if left unrepaired. Get to a service location before highway-speed loads.
How much does it cost to fix P1248 on a commercial truck?
Total repair cost ranges $100–$4000 depending on the root cause. The cheapest fix is usually the first one listed below — Sticking timing control solenoid or timing piston in the injection pump — which is also the most common. On commercial trucks the cost is usually higher than passenger vehicles due to part availability and shop labor rates ($120–185/hour at most truck shops, vs $90–130 at general auto shops). DIY-capable fixes (sensors, hoses, filters) are at the low end; major component replacements (turbo actuator, high-pressure fuel pump, transmission solenoid pack) are at the high end. Always diagnose with a scan tool BEFORE replacing parts — guessing wrong on a $1,500 turbo actuator when the actual issue was a $30 boost hose is a common expensive mistake.
Will P1248 fail a DOT inspection?
P1248 itself doesn't automatically fail an inspection, but if the truck is in reduced-power mode (limp mode) at the time of inspection, it WILL be flagged. Most inspectors will note the check engine light but pass the truck if it's running and performance is normal. Fix it before a Level 1 inspection regardless.
What's the difference between P1248 and related codes?
P1248 is closely related to: P1213 (Fuel Pressure Relief Valve), P1228 (Fuel Pump Speed Control Circuit), P1229 (Fuel Heater Circuit), P1241 (Engine Control Module Switch Sensing Voltage Too Low). These codes share the same subsystem (fuel) and often appear together. If you see this code, scan for the full code list — fixing the root cause usually clears multiple companion codes at once. If only P1248 is set without the companions, the issue is more isolated.
How do I prevent P1248 from coming back after a repair?
For P1248 (Injection Timing Control Circuit Performance), prevention centers on the fuel system. Replace fuel filters at the OEM interval — don't stretch them. Use only diesel from high-volume fuel stops (avoid bottom-of-tank fuel at low-traffic stations). Add a water separator if you don't have one. After repair, prime the fuel system per the engine manual.