Q: My 2008 Chevy Impala 3500 V6 has its computer state "Engine power down" and then dings. The engine light goes on. The engine powers down. Then it goes away in 15 minutes, but the engine light stays on and goes out the next day. I clean the gas cap and make sure it's on tight and put Seafoam in the gas tank — 400 miles later the computer states "Engine power down" and then dings. The engine light goes on, but the engine does not power down. The next day the engine light goes out — 300 miles it does it again, same as the second time. What can I do to correct this behavior?

A: I checked my ALLDATA automotive database and found GM service bulletin 14582A: Special Coverage Adjustment — Throttle body — Reduced Power Mode, dated October 2015. If a scan tool check pulls up fault codes DTC P2135, P0121 or P0221, the throttle body needs to be replaced. Bosch throttle bodies need to be replaced as a complete unit whereas Hitachi throttle bodies may need only a throttle position sensor kit. GM issued an extended warranty covering this repair for 10 years/120,000 miles from the date the vehicle was originally placed in service, regardless of ownership changes.

If fault code DTC P2135 is recorded in computer memory, a thorough cleaning of the throttle body and replacement of the TPS cover may solve the problem.

Another possibility for the same symptom, according to service bulletin 07-06-04-019E, is water intrusion into the instrument panel body harness connector to the ECM/PCM. A check for DTC P2138, a throttle pedal position sensor fault, would confirm this problem.

Q: When my dad died at 93 in 2009, I purchased his mint condition 2002 Buick LeSabre and have kept it "pristine" in his honor. It now has 171,000 miles and is simply wearing out. I have replaced axles and torn axle "boots" at least five times in the past seven years. Do any of your repair data bases — or from your own experience — deal with causation of these frequent axle and "boot" repairs?

A: The environment you live in — Minnesota — with its salt-encrusted snowy roads in winter, increases the stress on the rubber "boots" surrounding the constant-velocity joints on front-drive axles. Stiff boots in subfreezing weather are more likely to crack, allowing the escape of grease and intrusion of water, dirt and salt, leading to shorter life expectancy for the CV joint/axle. Other factors could include lesser quality aftermarket replacement boots and/or poor installation.

After suffering through the nasty, greasy, difficult knuckle-busting bondage of replacing torn boots on several axles, I decided to make the job easier, faster and less messy by replacing the drive axle assembly with a quality "reman" unit.

Q: I'm looking at buying a used Ford Explorer. Rumor has it the water pump is inside the engine and is very expensive to fix. Is this true?

A: Between the 2010 and 2011 model years, Ford changed from the 4-liter V6 to a 3.5-liter V6 engine. While the 4-liter is fitted with a conventional belt-driven front mounted water pump, the newer 3.5-liter engine has an internally mounted, timing chain-driven water pump requiring significant time and expense to replace. The "book" labor rate for this repair is 10.8 hours.

Motoring note: I received an e-mail from Joe Michaels regarding LT tire inflation. "I noted in the final paragraph of that article, you recommended inflating the tires in question to 44 psi after the writer stated that the maximum inflation rating on the tire's sidewall was 40 psi. This could imply that overinflation would increase tire or vehicle load-carrying capacity."

Thanks, Joe. I should have made clear that 44 psi is the max inflation pressure for the OE P275/70R17 tire, not 40 psi as the writer indicated. This tire would not be overinflated at 44 psi.

Paul Brand is the author of "How to Repair Your Car" and "How to Repair Your Truck and SUV," published by Motorbooks.