Bmw 318 P1799 Engine Trouble Code
What is Bmw 318 P1799?
The Bmw 318 P1799 check-engine light can indicate issues ranging from minor (loose gas cap) to serious (catalytic converter failure). Professional diagnostic scanning at a dealer or shop will identify the exact cause and required repairs.
P1799 on the Bmw 318
The Bmw 318 features a sequential multi-port fuel injection (SMFI) system where injector timing is tightly synchronised with the crankshaft signal. Wear on the crankshaft reluctor ring teeth produces signal dropout events that accumulate and eventually trigger P1799.
Code Information
| Code Type: | OBD-II Powertrain (P) Trouble Code |
| System: | Powertrain |
| Vehicle: | Bmw 318 |
| Brand: | Bmw |
| Model: | 318 |
| Code: | P1799 |
P1799 Bmw 318 Symptoms
Check Engine Light
Illuminated Bmw 318 dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Bmw 318
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Bmw 318
Increased Emissions
Failed emissions test due to P1799
P1799 Code Structure
Understanding what each digit means in the P1799 powertrain trouble code:
| P | 1 | 7 | 9 | 9 |
|---|---|---|---|---|
| Powertrain Code | Fuel And Air Metering | Fuel Rail Pressure Sensor Circuit Malfunction | Crankshaft Position Sensor A Circuit Malfunction | Reverse Input Circuit |
How to Fix Bmw 318 P1799
Diagnostic Steps:
Check if fuel pump primes when key is turned to ON. Measure fuel pressure and verify bright white-blue spark at all plugs. Also verify mechanical timing alignment.
Repair Solution:
A/C pressure sensor monitors refrigerant pressure changes. DTC sets when pressure change falls outside calibration. Verify A/C system function, refrigerant charge, and electrical connections.
Technical Notes:
For P1799, verify VCT solenoid operation. Look for stuck or sticking valves caused by contamination. Consult vehicle-specific repair manual for proper component testing procedures.
Bmw 318 P1799 Repair Cost
For Bmw 318 owners, budget the following for a P1799 repair: EGR valve cleaning $80–$120 or replacement $250–$450, intake manifold gasket $120–$200, and a post-repair reset and road test. Total: $350–$650 at an independent garage.
P1799 Description
P1799 engine trouble code is related to Reverse Input Circuit.
Main Cause
The primary reason for P1799 OBD-II Engine Trouble Code is: Fuel Rail Pressure Sensor Circuit Malfunction.
Common P1799 Misdiagnosis on the Bmw 318
When Bmw 318 presents P1799 with a concurrent coolant temperature DTC, technicians sometimes replace the thermostat rather than the coolant temperature sensor (CTS). The CTS is a $15–$25 component; the thermostat job carries 1–2 hours of additional labour.
DIY Repair Guide: P1799 on Bmw 318
The coolant temperature sensor on the Bmw 318 is a straightforward DIY item (difficulty 2/5). Have a drain tray ready for the small amount of coolant that spills when the sensor is removed. Top up the cooling system afterwards and check for air pockets.
Preventing P1799 on the Bmw 318
Inspecting the Bmw 318 wiring harness conduit grommets annually — especially the floor pan grommet — costs nothing and takes 10 minutes. Catching moisture ingress early eliminates the most common electrical trigger for P1799 on this model.
Frequently Asked Questions — Bmw 318 P1799
A: Yes. A weak battery causes voltage drop during cranking that confuses the ECU and can store a range of fault codes. Always rule out battery and charging system health before diagnosing sensor-related codes.