Gmc Suburban P1642 Engine Trouble Code
What is Gmc Suburban P1642?
The Gmc Suburban 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 Suburban
A known issue on the Gmc Suburban is that aftermarket air filter upgrades can inadvertently trigger P1642. High-flow filters alter the intake resonance frequency, causing the MAP sensor to report pressure readings outside factory calibration.
Code Information
| Code Type: | OBD-II Powertrain (P) Trouble Code |
| System: | Powertrain |
| Vehicle: | Gmc Suburban |
| Brand: | Gmc |
| Model: | Suburban |
| Code: | P1642 |
P1642 Gmc Suburban Symptoms
Check Engine Light
Illuminated Gmc Suburban dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Gmc Suburban
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Gmc Suburban
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 Suburban 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:
Gasoline engines use spark plugs to ignite fuel-air mixture. Proper timing ensures the explosion occurs when the piston is positioned correctly. Incorrect plug wire sequencing causes mistimed ignition, resulting in poor performance.
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 Suburban P1642 Repair Cost
For Gmc Suburban diesel variants with swirl flap actuator failure causing P1642, the repair ranges from $180 (actuator only) to $900+ if a broken flap has been ingested by the engine. Early intervention is strongly recommended.
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 Suburban
Some Gmc Suburban 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 Suburban
Replacing the spark plugs on the Gmc Suburban 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 Suburban
The Gmc Suburban coolant temperature sensor plays a role in fuel enrichment during warm-up. Replacing it as a precaution at 80,000 miles ($25–$40 DIY) prevents the faulty cold-start enrichment that can lead to P1642.
Frequently Asked Questions — Gmc Suburban P1642
A: Yes. Any stored fault code — including P1642 — will cause an automatic failure in most OBD-II based emissions tests. The code must be resolved and the vehicle must complete a full OBD drive cycle with no new codes before the test.