Gmc Terracross P1642 Engine Trouble Code
What is Gmc Terracross P1642?
Gmc Terracross P1642 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.
P1642 on the Gmc Terracross
The Gmc Terracross ECU flash version prior to the 2.4.1 update has a known calibration bug that can generate spurious P1642 codes under hard deceleration. Verifying the ECU software version is always the first step before any mechanical diagnosis on this model.
Code Information
| Code Type: | OBD-II Powertrain (P) Trouble Code |
| System: | Powertrain |
| Vehicle: | Gmc Terracross |
| Brand: | Gmc |
| Model: | Terracross |
| Code: | P1642 |
P1642 Gmc Terracross Symptoms
Check Engine Light
Illuminated Gmc Terracross dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Gmc Terracross
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Gmc Terracross
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 Terracross P1642
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:
P1642 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.
Gmc Terracross P1642 Repair Cost
For Gmc Terracross owners, budget the following for a P1642 repair: EGR valve cleaning $80–$120 or replacement $250–$450, intake manifold gasket $120–$200, and a post-repair reset and road test. Total: $350–$650 at an independent garage.
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 Terracross
Some Gmc Terracross models have a known software bug where the PCM flags P1642 after battery disconnection and reconnect. Always perform an ECU adaptation reset and drive cycle before ordering any parts following battery work.
DIY Repair Guide: P1642 on Gmc Terracross
For Gmc Terracross owners without a scan tool, a free diagnostic check is available at most franchised Gmc dealers during a courtesy health-check appointment. This provides the DTC number needed to research the exact cause of P1642 before committing to any repair.
Preventing P1642 on the Gmc Terracross
For turbocharged Gmc Terracross models, allowing the engine to idle for 60–90 seconds before shutdown after hard driving reduces turbocharger heat soak and prevents the coking of oil that blocks VVT galleries — a known secondary trigger of P1642.
Frequently Asked Questions — Gmc Terracross P1642
A: Almost certainly yes. Most faults that trigger P1642 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.