P0068 on 2006-2010 GMC Savana: MAP/MAF & Throttle Position Fixes

What's Unique About the 2006-2010 Gmc SAVANA

For this generation of GMC Savana, especially on higher mileage examples, code P0068 is frequently linked to issues beyond just a single bad sensor. A GM Technical Service Bulletin (PIP4578B) directly connects this code to problems like idle surges and reduced engine power, often stemming from a dirty or worn throttle body. As these vans age, carbon buildup becomes so common that cleaning the throttle body and performing an idle relearn procedure should be considered a primary diagnostic step. Owners should be wary of immediately replacing sensors, as the root cause is often unmetered air from vacuum leaks or incorrect airflow readings due to carbon buildup on the throttle plate.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on
• Engine running rough, especially at idle
• Vehicle enters 'Reduced Engine Power' or 'limp mode'
• Hesitation or sluggish acceleration
• Poor fuel economy
• Possible stalling at stops

Most Likely Causes

1. Dirty or Clogged Throttle Body 🔴 High Probability → Shop Fuel Injection Throttle Body As noted in TSB PIP4578B, carbon and grime accumulate in the throttle body over time, especially on high-mileage vans used for commercial purposes. This buildup can prevent the throttle plate from moving smoothly or closing properly, causing a mismatch between its commanded position and the actual airflow.
   How to confirm: Remove the air intake tube connected to the throttle body. Visually inspect the throttle bore and plate for a layer of black, sooty carbon buildup. Manually move the throttle plate to check for any sticking or binding.
   Typical fix: Clean the throttle body thoroughly with a dedicated throttle body cleaner and a soft brush or rag, ensuring both sides of the plate and the entire bore are clean. After cleaning, an 'Idle Learn Reset' must be performed with a scan tool or a manual procedure to allow the PCM to relearn the clean throttle's position. If cleaning doesn't work, the throttle body may be worn and require replacement.
   Est. part cost: $5 - $15 for cleaner, $150 - $300 for a new throttle body
2. Vacuum Leak 🔴 High Probability The large V8 engines in these vans generate significant heat, causing plastic and rubber components like intake manifold gaskets and PCV system hoses to become brittle and crack over time, leading to unmetered air entering the engine.
   How to confirm: Perform a smoke test. This involves introducing smoke into the intake system and watching for where it escapes. Alternatively, with the engine running, you can carefully spray brake cleaner or carb cleaner around suspected leak areas like the intake manifold gasket seams; a noticeable change in engine idle indicates a leak has been found.
   Typical fix: Replace the leaking gasket or hose. Intake manifold gaskets are a common failure point and can be a significant repair.
   Est. part cost: $5 - $50 for hoses, $40 - $100 for intake manifold gaskets
3. Faulty Manifold Absolute Pressure (MAP) Sensor 🟡 Medium Probability → Shop Manifold Absolute Pressure Sensor
   How to confirm: Use a scan tool to monitor the MAP sensor voltage. With the key on and engine off, it should read around 4.5-5.0 volts. At idle, it should drop to around 1.0-1.5 volts. The sensor is located at the top rear of the intake manifold, requiring removal of the engine 'doghouse' for access.
   Typical fix: Replace the MAP sensor. This involves removing the engine cover ('doghouse') for access, disconnecting the electrical connector, removing the retaining bolt, and pulling the old sensor out of the manifold.
   Est. part cost: $40 - $110
4. Dirty or Faulty Mass Air Flow (MAF) Sensor 🟡 Medium Probability → Shop Fuel Injection Air Flow Meter
   How to confirm: The MAF sensor can often be cleaned before it's condemned. Inspect the sensor wires inside the housing for dirt or debris. Use a scan tool to monitor airflow in grams/second (g/s) and compare to specified values for your engine at idle and under load. A typical V8 should read around 4-7 g/s at idle.
   Typical fix: First, try cleaning the sensor with a dedicated MAF sensor cleaner spray. Do not touch the delicate sensor wires. If cleaning doesn't resolve the issue, replace the MAF sensor assembly.
   Est. part cost: $10 - $20 for cleaner, $70 - $250 for a new sensor

Rare But Worth Checking

• Clogged Air Filter: A severely clogged air filter can restrict airflow enough to cause a correlation error. This is a simple and inexpensive check that should be part of routine maintenance.
• Damaged Wiring or Connectors: Inspect the wiring harnesses for the MAP, MAF, and throttle body for any signs of chafing, corrosion, or loose pins, especially given the work-van environment these vehicles operate in. Water intrusion into the throttle actuator control (TAC) module connector is also a possibility.
• Faulty Accelerator Pedal Position (APP) Sensor: The APP sensor tells the PCM how far you're pressing the gas pedal. If it sends faulty signals, it can conflict with the data from the throttle body and airflow sensors, triggering P0068. This is less common but has been noted in forum discussions.
• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is extremely rare. The PCM should only be considered as the cause after all other possibilities, including sensors, wiring, and vacuum leaks, have been exhaustively tested and ruled out.

Diagnosis Steps

1. Scan the PCM for P0068 and any other stored codes. Note any related throttle, MAF, or MAP sensor codes.
2. Visually inspect the entire air intake system from the air filter to the throttle body for loose clamps, cracked hoses, or disconnected lines.
3. Inspect and clean the Mass Air Flow (MAF) sensor using a dedicated MAF cleaner spray.
4. Remove the intake duct from the throttle body and inspect for heavy carbon buildup. Clean it thoroughly with throttle body cleaner, a toothbrush, and a rag, making sure to clean the back of the throttle plate and the bore.
5. After cleaning the throttle body, perform an 'Idle Learn Reset' with a capable scan tool. This step is critical per TSB PIP4578B.
6. Perform a smoke test on the intake system to check for vacuum leaks 🎬 Watch: How to perform a quick and effective smoke test. that are not visually apparent. Pay close attention to the intake manifold gaskets and PCV system hoses.
7. With a scan tool, monitor the live data for the Throttle Position, MAP sensor (kPa or V), and MAF sensor (g/s) at idle and while slowly increasing engine RPM. Look for any sensor whose readings do not change smoothly or seem illogical compared to the others.
8. If a sensor is suspected after the above steps, test its wiring for proper voltage and ground before replacing the part. Check for 5-volt reference, ground, and signal wire integrity.

Parts You'll Likely Need

• Throttle Body Assembly (OEM #19420713 (replaces 12570800)) — Often the root cause due to carbon buildup or electronic failure, as highlighted by TSB PIP4578B. Cleaning is the first step, but replacement is common on high-mileage vans.
  Trusted brands: ACDelco, Hitachi, Dorman
  OEM price range: $200-$350
  Aftermarket price range: $150-$250
• Manifold Absolute Pressure (MAP) Sensor (OEM #19418812) — This sensor provides critical engine load data. If it fails, it will directly cause a correlation error.
  Trusted brands: ACDelco, Delphi, Bosch
  OEM price range: $60-$110
  Aftermarket price range: $30

Related Codes That Often Appear With This One

• P0121 — Throttle/Pedal Position Sensor/Switch 'A' Circuit Performance. This code is often seen with P0068 as both relate to the throttle body's performance and is mentioned in TSB PIP4578B.
• P1516 — Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance. This indicates a problem with the electronic throttle control system, directly related to P0068 and also cited in TSB PIP4578B.
• P2101 — Control Module Throttle Actuator Control Motor Circuit Range/Performance. Another code pointing to the electronic throttle body, often triggered alongside P0068 as noted in TSB PIP4578B.
• P0101 — Mass Air Flow (MAF) Circuit Range/Performance. This code indicates a problem specifically with the MAF sensor's readings, which is a primary input for the P0068 correlation check.
• P0106 — Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance. This points to an issue with the MAP sensor's readings, another primary input for the P0068 calculation, and is often seen with it.

Technical Service Bulletins (TSBs) & Recalls

• SES Light, Idle Surge, and/or Reduced Engine Power Mode with DTCs P0068...: This TSB is central to diagnosing P0068 on high-mileage GM trucks and vans. It states that as carbon builds up, the PCM learns to open the throttle plate more at idle. If the throttle body is cleaned (or the PCM is reprogrammed/replaced) without resetting this learned value, the idle will be incorrect and can set various codes, including P0068. The official fix is to clean the throttle body thoroughly and then perform an 'Idle Learn Reset' with a GM Tech 2 or equivalent scan tool.

Platform-Specific Known Issues

• Engine Cover ('Doghouse') Access: On the GMC Savana, the engine is located partially inside the cabin under a removable cover known as the 'doghouse'. To access components at the back of the engine, like the MAP sensor, this cover must be removed. This can make diagnosis and repair more time-consuming compared to a vehicle with a traditional hood.
• Required Idle Relearn Procedure: As detailed in TSB PIP4578B, after cleaning the throttle body or replacing it, it is critical to perform an 'Idle Learn Reset' using a capable scan tool like a Tech 2. The PCM has learned to compensate for the carbon buildup over time. If this learned data is not reset, the engine may idle too high or run poorly even after the cleaning, potentially causing new trouble codes.

Mechanic-Grade Diagnostic Values

• Mass Air Flow (MAF) Sensor Reading at Idle (Scan Tool) — expected: 4-7 g/s for a V8 engine.. Failure: Readings are stuck, erratic, zero, or do not rise smoothly with engine RPM.
• Mass Air Flow (MAF) Sensor Reading at 2500 RPM (Scan Tool) — expected: 15 to 25 g/s.. Failure: Reading does not rise significantly from idle or is erratic.
• Mass Air Flow (MAF) Sensor Signal Frequency at Idle (Multimeter) — expected: ~3.2 KHz at ~680 RPM.. Failure: Frequency is stuck or does not correspond to engine RPM.
• Throttle Position Sensor (TPS) Voltage (Scan Tool/Multimeter) — expected: ~0.5V at closed throttle, rising to ~4.5V at wide-open throttle.. Failure: Voltage is erratic, does not change smoothly, or is outside the expected range.
• Manifold Absolute Pressure (MAP) Sensor Voltage (KOEO) — expected: 4.5 - 5.0 Volts (Key On, Engine Off).. Failure: Voltage is significantly lower, indicating a sensor or wiring issue.

Scan Tool Commands That Help

• Tech2/GDS2 or capable OBD-II Scanner: Idle Learn Reset / Throttle Learn — This function must be used after cleaning or replacing the throttle body to allow the ECM to relearn the new closed throttle position. Failing to do this is a common cause of continued idle problems after the physical repair.

Wiring & Ground Locations

• G103 — Located at the left rear of the engine compartment on the cowl, above the brake booster.. This is a primary ground location for the Body Control Module (BCM), Instrument Panel Cluster (IPC), and the Data Link Connector (DLC). A poor connection here can cause erratic sensor readings and communication issues between modules, potentially contributing to a P0068 code.
• Throttle Body Connector — The 6-pin electrical connector on the electronic throttle body assembly.. This connector contains the wiring for the two Throttle Position (TP) sensors and the throttle actuator control (TAC) motor. Testing for 5V reference, ground, and signal integrity at these pins is crucial for diagnosing a faulty throttle body versus a wiring problem.
• Engine to Frame Ground Strap — Typically a bare braided copper strap running from the engine block or transmission to the vehicle's frame.. Ensures the engine, ECM, and all sensors share a common ground plane with the battery. A corroded or broken strap can create voltage differentials, leading to incorrect sensor readings and phantom codes like P0068.

Real Owner Repair Stories

• PerformanceTrucks.net Forums (2006-2009 GM Truck/SUV (specific vehicle not stated, but TSB applies to Savana)) — Reduced Engine Power (REP), codes P0068 and P0106.
  ❌ Tried (didn't work) Replacing the MAP sensor, Replacing the DBW Throttle Body, Checking wiring and grounds, Checking spark plugs and wires
  ✅ What actually fixed it The user was directed to GM TSB #PIP4578A (a predecessor to the one cited in the main article), which instructs to clean the throttle body and perform an idle learn reset. This was the prescribed fix for the combination of codes and symptoms.

OEM Part Supersession History

• 12570800 → 19420713 — Standard part lifecycle update by the manufacturer.
  Heads up: The new part number is the direct, recommended replacement for the original.

Model Year Variations Within This Range

• 2007 vs. 2009 (example): While within the same generation, GM sometimes made minor changes to throttle body designs between model years (e.g., NNBS truck intakes). While the Savana is less documented, it's crucial to verify the part number or visually match the old throttle body, as subtle differences in the bore or connector can exist.