Gmc Terrain P1642 Engine Trouble Code
What is Gmc Terrain P1642?
Gmc Terrain P1642 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.
P1642 on the Gmc Terrain
On high-mileage Gmc Terrain examples, P1642 is often the first sign of a failing fuel pressure regulator. Residual fuel pressure bleeds off overnight, causing lean-start conditions that the ECU registers as a fault at the next cold start.
Code Information
| Code Type: | OBD-II Powertrain (P) Trouble Code |
| System: | Powertrain |
| Vehicle: | Gmc Terrain |
| Brand: | Gmc |
| Model: | Terrain |
| Code: | P1642 |
P1642 Gmc Terrain Symptoms
Check Engine Light
Illuminated Gmc Terrain dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Gmc Terrain
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Gmc Terrain
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 Terrain P1642
Diagnostic Steps:
Regarding P1642, 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:
Disconnected, dirty, or fouled spark plugs commonly prevent proper engine operation. Replace spark plugs every season or 25 hours. Verify proper spark plug gap. If plugs are good, check ignition components: spark plug wires, coils, and ignition module.
Technical Notes:
Parts or components should not be replaced based solely on P1642 DTC. Consult your vehicle service manual for proper diagnostic procedures, possible causes, and required testing before replacement.
Gmc Terrain P1642 Repair Cost
For Gmc Terrain 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 Terrain
The Gmc Terrain is frequently taken to workshops for a P1642 fault where the technician replaces the throttle position sensor (TPS). In a significant proportion of cases, the root cause is a loose or cracked vacuum hose downstream of the throttle body that should have been found in a basic visual inspection.
DIY Repair Guide: P1642 on Gmc Terrain
The throttle body on the Gmc Terrain 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 Terrain
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 P1642 on the Gmc Terrain.
Frequently Asked Questions — Gmc Terrain P1642
A: Yes. A weak battery causes voltage drop during cranking that confuses the ECU and can store a range of fault codes. Always rule out battery and charging system health before diagnosing sensor-related codes.