Gmc Envoy P1642 Engine Trouble Code
What is Gmc Envoy P1642?
The Gmc Envoy P1642 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.
P1642 on the Gmc Envoy
Diesel variants of the Gmc Envoy trigger P1642 most often due to swirl flap actuator failure. The plastic actuator arm breaks and the flap defaults to the closed position, causing severe intake restriction and the associated fault flag.
Code Information
| Code Type: | OBD-II Powertrain (P) Trouble Code |
| System: | Powertrain |
| Vehicle: | Gmc Envoy |
| Brand: | Gmc |
| Model: | Envoy |
| Code: | P1642 |
P1642 Gmc Envoy Symptoms
Check Engine Light
Illuminated Gmc Envoy dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Gmc Envoy
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Gmc Envoy
Increased Emissions
Failed emissions test due to P1642
P1642 Code Structure
Understanding what each digit means in the P1642 powertrain trouble code:
| P | 1 | 6 | 4 | 2 |
|---|---|---|---|---|
| Powertrain Code | Fuel And Air Metering | Fuel Temperature Sensor B Circuit Range/Performance | Injection Pump Fuel Metering Control 'B' High | Glow Plug/Heater Circuit 'A' Malfunction |
How to Fix Gmc Envoy P1642
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:
P1642 on electronically controlled automatic transmissions relates to shift solenoid operation. The solenoid actuates hydraulic circuits controlling clutches or bands for gear changes.
Gmc Envoy P1642 Repair Cost
A fuel pressure regulator replacement on the Gmc Envoy runs $180–$320 at a specialist. Fuel system work requires depressurisation procedures, so this is not typically a DIY job. Some workshops include a full fuel injector flow test (value: $80) at no extra charge.
P1642 Description
P1642 engine trouble code is related to Glow Plug/Heater Circuit 'A' Malfunction.
Main Cause
The primary reason for P1642 OBD-II Engine Trouble Code is: Fuel Temperature Sensor B Circuit Range/Performance.
Common P1642 Misdiagnosis on the Gmc Envoy
When P1642 triggers on the Gmc Envoy, a flashing check-engine light (as opposed to a steady one) indicates an active misfire. Misfire codes are commonly misdiagnosed as sensor faults; always rule out ignition and fuel delivery issues before testing sensors.
DIY Repair Guide: P1642 on Gmc Envoy
The throttle body on the Gmc Envoy can be cleaned without full removal. Use a clean rag and throttle body cleaner spray with the engine off and cool. After cleaning, an idle relearn is mandatory: disconnect the battery for 10 minutes, reconnect, and allow the engine to idle for 10 minutes undisturbed.
Preventing P1642 on the Gmc Envoy
To keep the Gmc Envoy free of recurring P1642 faults, change the engine oil every 5,000–7,500 miles using a grade specified by Gmc. Oil viscosity directly affects VVT actuator response, and using the wrong grade is one of the most avoidable causes of this code.
Frequently Asked Questions — Gmc Envoy P1642
A: P1642 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 Gmc Envoy.