Toyota Mrj P1629 Engine Trouble Code
What is Toyota Mrj P1629?
Toyota Mrj 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 Toyota Mrj
The turbocharged variants of the Toyota Mrj are more likely to generate P1629 as boost-related over-fuelling trips the ECU threshold. Inspect the intercooler hoses for micro-cracks that allow unmetered air into the intake stream.
Code Information
| Code Type: | OBD-II Powertrain (P) Trouble Code |
| System: | Powertrain |
| Vehicle: | Toyota Mrj |
| Brand: | Toyota |
| Model: | Mrj |
| Code: | P1629 |
P1629 Toyota Mrj Symptoms
Check Engine Light
Illuminated Toyota Mrj dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Toyota Mrj
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Toyota Mrj
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 Toyota Mrj 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:
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.
Toyota Mrj P1629 Repair Cost
Throttle body cleaning and idle relearn on the Toyota Mrj for a P1629 diagnosis costs $60–$100 at an independent shop. If a full throttle body replacement is needed (rare), expect $250–$450 including programming the unit to the ECU.
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 Toyota Mrj
Fuel injector replacement is over-prescribed on the Toyota Mrj for P1629 when the actual fault is a weak fuel pump. Low fuel rail pressure causes lean misfire that looks identical to injector failure in static scan data without a live fuel pressure test.
DIY Repair Guide: P1629 on Toyota Mrj
Battery terminal cleaning on the Toyota Mrj is a 5-minute job that resolves a surprising number of P1629 intermittents. Use a wire brush and a bicarbonate of soda solution to clean corrosion, then apply a thin coat of petroleum jelly to the terminals after refitting.
Preventing P1629 on the Toyota Mrj
The Toyota Mrj benefits from an intake manifold decarbonisation at 50,000-mile intervals when direct injection is fitted. Carbon build-up on intake valve stems restricts airflow and creates the lean conditions that trigger P1629.
Frequently Asked Questions — Toyota Mrj 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.