Chevrolet Vectra P1629 Engine Trouble Code
What is Chevrolet Vectra P1629?
When Chevrolet Vectra P1629 code appears, first check your gas cap. Pull over safely, ensure it is tight, and inspect for cracks. A loose or damaged gas cap affects fuel-system pressure and emissions. A replacement cap costs about $3–$10. This simple fix can resolve the code and improve fuel economy.
P1629 on the Chevrolet Vectra
In cold climates, Chevrolet Vectra vehicles frequently log P1629 during the first winter of ownership. Condensation inside the throttle body creates a temporary short circuit in the position sensor wiring, which clears once the engine warms up — but the fault code remains stored.
Code Information
| Code Type: | OBD-II Powertrain (P) Trouble Code |
| System: | Powertrain |
| Vehicle: | Chevrolet Vectra |
| Brand: | Chevrolet |
| Model: | Vectra |
| Code: | P1629 |
P1629 Chevrolet Vectra Symptoms
Check Engine Light
Illuminated Chevrolet Vectra dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Chevrolet Vectra
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Chevrolet Vectra
Increased Emissions
Failed emissions test due to P1629
P1629 Code Structure
Understanding what each digit means in the P1629 powertrain trouble code:
| P | 1 | 6 | 2 | 9 |
|---|---|---|---|---|
| Powertrain Code | Fuel And Air Metering | Fuel Temperature Sensor B Circuit Range/Performance | Turbocharger Boost Sensor A Circuit Low | Reverse Input Circuit |
How to Fix Chevrolet Vectra P1629
Diagnostic Steps:
Oxygen sensors measure exhaust gas oxygen content to optimise air-fuel ratio. This optimisation improves fuel economy and reduces emissions. Sensors degrade over time and require periodic replacement.
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:
P1629 on electronically controlled automatic transmissions relates to shift solenoid operation. The solenoid actuates hydraulic circuits controlling clutches or bands for gear changes.
Chevrolet Vectra P1629 Repair Cost
Replacing the lambda (O2) sensor wiring loom section on the Chevrolet Vectra costs $90–$160 at a body shop or auto-electrician. This is far cheaper than replacing the sensor itself when the sensor is otherwise functional — always inspect wiring before condemning sensors.
P1629 Description
P1629 engine trouble code is related to Reverse Input Circuit.
Main Cause
The primary reason for P1629 OBD-II Engine Trouble Code is: Fuel Temperature Sensor B Circuit Range/Performance.
Common P1629 Misdiagnosis on the Chevrolet Vectra
The Chevrolet Vectra knock sensor shares its harness with the coolant temperature sensor. A corroded shared ground causes both sensors to report out-of-range values simultaneously, leading to misdiagnosis of P1629 as a knock sensor fault when the root cause is the shared ground splice.
DIY Repair Guide: P1629 on Chevrolet Vectra
The fuel pressure test on the Chevrolet Vectra requires a Schrader-valve type fuel pressure gauge ($25–$40) connected to the fuel rail test port. With the ignition ON (engine off), pressure should hold above 30 PSI for two minutes. A rapid drop confirms a leaking injector or failing regulator as the root cause of P1629.
Preventing P1629 on the Chevrolet Vectra
Inspecting the Chevrolet Vectra 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 P1629 on this model.
Frequently Asked Questions — Chevrolet Vectra P1629
A: P1629 is a standardised OBD-II code that can appear on any make and model. However, the specific components and circuits that trigger this code, and the repair procedures involved, vary significantly between vehicles. The information on this page is focused on the Chevrolet Vectra.