Bmw 325 P1629 Engine Trouble Code
What is Bmw 325 P1629?
Bmw 325 P1629 indicates potential catalytic converter failure. If completely failed, your vehicle may not run properly and fuel economy will suffer significantly. Average replacement cost is $2,000–$2,140. This repair requires professional service and should not be delayed.
P1629 on the Bmw 325
The Bmw 325 is particularly susceptible to P1629 faults when the engine management unit receives conflicting sensor data. Owners report that P1629 on Bmw 325 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: | Bmw 325 |
| Brand: | Bmw |
| Model: | 325 |
| Code: | P1629 |
P1629 Bmw 325 Symptoms
Check Engine Light
Illuminated Bmw 325 dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Bmw 325
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Bmw 325
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 Bmw 325 P1629
Diagnostic Steps:
The catalytic converter has oxygen sensors before and after it. When warm and in closed-loop mode, the upstream O2 sensor reading should fluctuate, while downstream should remain steady.
Repair Solution:
Most manufacturers number cylinders sequentially from front to back. Ford V-engines start with cylinder 1 at front left. In V-6 engines, cylinder 4 is front right; in V-8 engines, cylinder 5 occupies that position.
Technical Notes:
For P1629, verify VCT solenoid operation. Look for stuck or sticking valves caused by contamination. Consult vehicle-specific repair manual for proper component testing procedures.
Bmw 325 P1629 Repair Cost
Intercooler hose replacement on turbocharged Bmw 325 models costs $120–$250 per section. A boost-leak smoke test ($50–$80) is the definitive diagnostic method and will pinpoint exactly which hose or connection is at fault before any parts are ordered.
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 Bmw 325
Many Bmw 325 owners have unnecessarily replaced the MAF sensor for P1629. In 60% of confirmed cases, the sensor was simply contaminated and required a $10 aerosol clean rather than a $200 replacement.
DIY Repair Guide: P1629 on Bmw 325
For the mechanically confident Bmw 325 owner, a DIY MAF sensor clean is a rewarding first step for P1629. Use a dedicated MAF sensor cleaner spray — not brake cleaner, which damages the sensing element — and allow the sensor to dry for 30 minutes before reinstallation.
Preventing P1629 on the Bmw 325
The Bmw 325 EVAP system requires the fuel tank breather hoses to be flexible and crack-free. A visual inspection at every oil change prevents the slow vacuum leak that triggers P1629 without any drivability symptom.
Frequently Asked Questions — Bmw 325 P1629
A: Yes. Some fault conditions, particularly those involving EVAP system leaks or marginal sensor readings, store codes without producing noticeable drivability symptoms. These are called memory faults and still need to be addressed because they will eventually cause performance issues.