Peugeot 508 P1799 Engine Trouble Code
What is Peugeot 508 P1799?
The Peugeot 508 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 Peugeot 508
The Peugeot 508 is particularly susceptible to P1799 faults when the engine management unit receives conflicting sensor data. Owners report that P1799 on Peugeot 508 most commonly surfaces after 60,000 miles, especially when routine service intervals have been missed.
Code Information
| Code Type: | OBD-II Powertrain (P) Trouble Code |
| System: | Powertrain |
| Vehicle: | Peugeot 508 |
| Brand: | Peugeot |
| Model: | 508 |
| Code: | P1799 |
P1799 Peugeot 508 Symptoms
Check Engine Light
Illuminated Peugeot 508 dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Peugeot 508
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Peugeot 508
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 Peugeot 508 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:
Firing order is engineered to minimise vibration. Altering firing order results in mistimed ignition and poor engine operation. Consult vehicle-specific repair manual for correct firing order.
Technical Notes:
P1799 on electronically controlled automatic transmissions relates to shift solenoid operation. The solenoid actuates hydraulic circuits controlling clutches or bands for gear changes.
Peugeot 508 P1799 Repair Cost
Torque converter clutch solenoid replacement on the Peugeot 508 — relevant for owners who tow regularly — costs $280–$480. A full transmission fluid change ($120–$160) at the same service is recommended because contaminated fluid accelerates solenoid wear.
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 Peugeot 508
On Peugeot 508 vehicles, the turbo boost solenoid and the MAP sensor feed into the same diagnostic path. P1799 caused by a faulty boost solenoid is sometimes charged to the customer as a MAP sensor replacement, doubling unnecessary parts spend.
DIY Repair Guide: P1799 on Peugeot 508
The coolant temperature sensor on the Peugeot 508 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 Peugeot 508
For turbocharged Peugeot 508 models, allowing the engine to idle for 60–90 seconds before shutdown after hard driving reduces turbocharger heat soak and prevents the coking of oil that blocks VVT galleries — a known secondary trigger of P1799.
Frequently Asked Questions — Peugeot 508 P1799
A: Almost certainly yes. Most faults that trigger P1799 cause the ECU to operate in open-loop mode or apply overly rich fuel trims, both of which increase fuel consumption by 5–15%. Resolving the fault promptly pays for itself in fuel savings over time.