Chevrolet Four Ninety P1629 Engine Trouble Code
What is Chevrolet Four Ninety P1629?
Chevrolet Four Ninety P1629 code can indicate a faulty oxygen sensor, which may eventually damage the catalytic converter (repair cost: $2,000–$2,200). Professional diagnosis costs around $200–$210. Oxygen sensors are often straightforward to replace — check your owner's manual for location and instructions. This issue should be addressed promptly to prevent further damage.
P1629 on the Chevrolet Four Ninety
The Chevrolet Four Ninety uses a dual-port fuel injection architecture that is sensitive to ethanol content variations. When E10 fuel is substituted with E5, or vice versa, the fuel trim corrections can cross the DTC threshold and store P1629 in the ECU.
Code Information
| Code Type: | OBD-II Powertrain (P) Trouble Code |
| System: | Powertrain |
| Vehicle: | Chevrolet Four Ninety |
| Brand: | Chevrolet |
| Model: | Four Ninety |
| Code: | P1629 |
P1629 Chevrolet Four Ninety Symptoms
Check Engine Light
Illuminated Chevrolet Four Ninety dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Chevrolet Four Ninety
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Chevrolet Four Ninety
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 Four Ninety P1629
Diagnostic Steps:
Regarding P1629, carefully inspect the wire harness near the intake manifold bracket, best accessed from below near the oil filter. Look for chafing, pinching, or damaged insulation.
Repair Solution:
Brake switch circuit concerns may involve open or shorted BPP circuits, damaged switches, or misadjustment. Verify stoplight function and follow proper self-test procedures per service manual.
Technical Notes:
P1629 DTC indicating a sensor fault does not always mean the sensor itself is bad. The issue may stem from the systems being monitored or even the sensor wiring. Proper diagnosis is essential.
Chevrolet Four Ninety P1629 Repair Cost
Ground circuit repairs on the Chevrolet Four Ninety — a common cause of P1629 — are labour-intensive but parts are cheap. Expect 1.5–2.5 hours of labour ($120–$200) to clean, treat, and re-torque all engine and transmission ground straps. This is excellent value given how often it resolves persistent fault codes.
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 Four Ninety
A catalytic converter is often condemned on the Chevrolet Four Ninety when P1629 appears and an efficiency code is present. Before replacement, verify that the upstream oxygen sensor is not slow-responding — a lazy O2 sensor mimics catalytic inefficiency perfectly.
DIY Repair Guide: P1629 on Chevrolet Four Ninety
When replacing sensors on the Chevrolet Four Ninety, always use anti-seize compound on the thread and dielectric grease on the electrical connector. This simple habit prevents the most common causes of sensor-related callbacks after repair.
Preventing P1629 on the Chevrolet Four Ninety
Spark plug replacement at the manufacturer's interval — typically 30,000–60,000 miles depending on plug type — is the single most cost-effective preventive maintenance item for avoiding P1629 on the Chevrolet Four Ninety.
Frequently Asked Questions — Chevrolet Four Ninety P1629
A: Almost certainly yes. Most faults that trigger P1629 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.