Gmc Safari P1642 Engine Trouble Code
What is Gmc Safari P1642?
Gmc Safari 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 Safari
Many Gmc Safari drivers first encounter P1642 as a result of worn ignition coil packs. The design of the Gmc engine bay can trap heat near these components, accelerating wear beyond the typical service interval.
Code Information
| Code Type: | OBD-II Powertrain (P) Trouble Code |
| System: | Powertrain |
| Vehicle: | Gmc Safari |
| Brand: | Gmc |
| Model: | Safari |
| Code: | P1642 |
P1642 Gmc Safari Symptoms
Check Engine Light
Illuminated Gmc Safari dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Gmc Safari
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Gmc Safari
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 Safari 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:
VSS concerns may stem from noisy input signals caused by RFI/EMI from ignition wires, charging circuits, or aftermarket equipment. Verify VSS reads 0 mph when transmission is in Park.
Technical Notes:
P1642 DTC specifically relates to camshaft timing. When cam timing is over-retarded, the check-engine light illuminates and this code sets. Verify VCT solenoid operation and check for contamination.
Gmc Safari P1642 Repair Cost
A complete diagnostic health-check on the Gmc Safari before committing to any single repair costs $120–$180 at a dealership with live-data capability. This investment pays for itself if it prevents unnecessary part replacement, which is the single most common mistake when diagnosing P1642.
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 Safari
Workshop technicians sometimes replace the entire ignition coil assembly on the Gmc Safari when P1642 accompanies a cylinder-specific misfire. In many cases, only the spark plug in the misfiring cylinder has fouled; a $8 plug replaces a $140 coil pack.
DIY Repair Guide: P1642 on Gmc Safari
Replacing the spark plugs on the Gmc Safari is rated a difficulty 2/5 for home mechanics. The top-mounted plug access on this engine requires a 3/8" extension and a 14mm spark plug socket. Always torque to the manufacturer's specification to avoid cracking the cylinder head.
Preventing P1642 on the Gmc Safari
Keeping the Gmc Safari battery in good health — testing specific gravity annually and replacing at first sign of degradation — protects the ECU voltage supply. Voltage drops during cranking cause sensor reading spikes that can spuriously store P1642.
Frequently Asked Questions — Gmc Safari P1642
A: If your Gmc Safari is within the factory powertrain warranty period (typically 3–5 years or 60,000–100,000 miles depending on region and generation), P1642 repairs caused by component defects should be covered. Bring your service history to the dealer appointment.